bus: ti-sysc: Fix warning on unbind if reset is not deasserted

We currently get thefollowing on driver unbind if a reset is configured
and asserted:

WARNING: CPU: 0 PID: 993 at drivers/reset/core.c:432 reset_control_assert
...
(reset_control_assert) from [<c0fecda8>] (sysc_remove+0x190/0x1e4)
(sysc_remove) from [<c0a2bb58>] (platform_remove+0x24/0x3c)
(platform_remove) from [<c0a292fc>] (__device_release_driver+0x154/0x214)
(__device_release_driver) from [<c0a2a210>] (device_driver_detach+0x3c/0x8c)
(device_driver_detach) from [<c0a27d64>] (unbind_store+0x60/0xd4)
(unbind_store) from [<c0546bec>] (kernfs_fop_write_iter+0x10c/0x1cc)

Let's fix it by checking the reset status.

Signed-off-by: Tony Lindgren <tony@atomide.com>