usb: dwc3: core: don't trigger runtime pm when remove driver

No need to trigger runtime pm in driver removal, otherwise if user
disable auto suspend via sys file, runtime suspend may be entered,
which will call dwc3_core_exit() again and there will be clock disable
not balance warning:

[ 2026.820154] xhci-hcd xhci-hcd.0.auto: remove, state 4
[ 2026.825268] usb usb2: USB disconnect, device number 1
[ 2026.831017] xhci-hcd xhci-hcd.0.auto: USB bus 2 deregistered
[ 2026.836806] xhci-hcd xhci-hcd.0.auto: remove, state 4
[ 2026.842029] usb usb1: USB disconnect, device number 1
[ 2026.848029] xhci-hcd xhci-hcd.0.auto: USB bus 1 deregistered
[ 2026.865889] ------------[ cut here ]------------
[ 2026.870506] usb2_ctrl_root_clk already disabled
[ 2026.875082] WARNING: CPU: 0 PID: 731 at drivers/clk/clk.c:958
clk_core_disable+0xa0/0xa8
[ 2026.883170] Modules linked in: dwc3(-) phy_fsl_imx8mq_usb [last
unloaded: dwc3]
[ 2026.890488] CPU: 0 PID: 731 Comm: rmmod Not tainted
5.8.0-rc7-00280-g9d08cca-dirty #245
[ 2026.898489] Hardware name: NXP i.MX8MQ EVK (DT)
[ 2026.903020] pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--)
[ 2026.908594] pc : clk_core_disable+0xa0/0xa8
[ 2026.912777] lr : clk_core_disable+0xa0/0xa8
[ 2026.916958] sp : ffff8000121b39a0
[ 2026.920271] x29: ffff8000121b39a0 x28: ffff0000b11f3700
[ 2026.925583] x27: 0000000000000000 x26: ffff0000b539c700
[ 2026.930895] x25: 000001d7e44e1232 x24: ffff0000b76fa800
[ 2026.936208] x23: ffff0000b76fa6f8 x22: ffff800008d01040
[ 2026.941520] x21: ffff0000b539ce00 x20: ffff0000b7105000
[ 2026.946832] x19: ffff0000b7105000 x18: 0000000000000010
[ 2026.952144] x17: 0000000000000001 x16: 0000000000000000
[ 2026.957456] x15: ffff0000b11f3b70 x14: ffffffffffffffff
[ 2026.962768] x13: ffff8000921b36f7 x12: ffff8000121b36ff
[ 2026.968080] x11: ffff8000119e1000 x10: ffff800011bf26d0
[ 2026.973392] x9 : 0000000000000000 x8 : ffff800011bf3000
[ 2026.978704] x7 : ffff800010695d68 x6 : 0000000000000252
[ 2026.984016] x5 : ffff0000bb9881f0 x4 : 0000000000000000
[ 2026.989327] x3 : 0000000000000027 x2 : 0000000000000023
[ 2026.994639] x1 : ac2fa471aa7cab00 x0 : 0000000000000000
[ 2026.999951] Call trace:
[ 2027.002401]  clk_core_disable+0xa0/0xa8
[ 2027.006238]  clk_core_disable_lock+0x20/0x38
[ 2027.010508]  clk_disable+0x1c/0x28
[ 2027.013911]  clk_bulk_disable+0x34/0x50
[ 2027.017758]  dwc3_core_exit+0xec/0x110 [dwc3]
[ 2027.022122]  dwc3_suspend_common+0x84/0x188 [dwc3]
[ 2027.026919]  dwc3_runtime_suspend+0x74/0x9c [dwc3]
[ 2027.031712]  pm_generic_runtime_suspend+0x28/0x40
[ 2027.036419]  genpd_runtime_suspend+0xa0/0x258
[ 2027.040777]  __rpm_callback+0x88/0x140
[ 2027.044526]  rpm_callback+0x20/0x80
[ 2027.048015]  rpm_suspend+0xd0/0x418
[ 2027.051503]  __pm_runtime_suspend+0x58/0xa0
[ 2027.055693]  dwc3_runtime_idle+0x7c/0x90 [dwc3]
[ 2027.060224]  __rpm_callback+0x88/0x140
[ 2027.063973]  rpm_idle+0x78/0x150
[ 2027.067201]  __pm_runtime_idle+0x58/0xa0
[ 2027.071130]  dwc3_remove+0x64/0xc0 [dwc3]
[ 2027.075140]  platform_drv_remove+0x28/0x48
[ 2027.079239]  device_release_driver_internal+0xf4/0x1c0
[ 2027.084377]  driver_detach+0x4c/0xd8
[ 2027.087954]  bus_remove_driver+0x54/0xa8
[ 2027.091877]  driver_unregister+0x2c/0x58
[ 2027.095799]  platform_driver_unregister+0x10/0x18
[ 2027.100509]  dwc3_driver_exit+0x14/0x1408 [dwc3]
[ 2027.105129]  __arm64_sys_delete_module+0x178/0x218
[ 2027.109922]  el0_svc_common.constprop.0+0x68/0x160
[ 2027.114714]  do_el0_svc+0x20/0x80
[ 2027.118031]  el0_sync_handler+0x88/0x190
[ 2027.121953]  el0_sync+0x140/0x180
[ 2027.125267] ---[ end trace 027f4f8189958f1f ]---
[ 2027.129976] ------------[ cut here ]------------

Fixes: fc8bb91b ("usb: dwc3: implement runtime PM")
Cc: <stable@vger.kernel.org>
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>