clk: imx7d: do not set the parent of IMX7D_ENET_AXI_ROOT_SRC

Booting the kernel on a imx7s-warp leads to several warnings like these:

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3536 lock_release+0x2f8/0x330
[    0.000000] releasing a pinned lock

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:2722 trace_hardirqs_on_caller+0x1ac/0x1f4
[    0.000000] DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))

[    0.000000] ---[ end trace cb88537fdc8fa201 ]---
[    0.000000] bad: scheduling from the idle thread!
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.7.0-rc7-next-20160715 #404

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8
[    0.000000] Modules linked in:

[    0.000591] ------------[ cut here ]------------
[    0.000610] WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:179 sched_clock_register+0x44/0x1f8

[    0.002084] ------------[ cut here ]------------
[    0.002104] WARNING: CPU: 0 PID: 0 at init/main.c:576 start_kernel+0x258/0x3b0
[    0.002114] Interrupts were enabled early

This fix is along the same lines as 5e33ebff ("clk: imx7d: do not
set parent of ethernet time/ref clocks") and the explanation from that
commit is:

"The reason for the warning is that setting the parent enables the ENET
 PLL since we are using CLK_OPS_PARENT_ENABLE. Enabling the ENET PLL can
 cause clk_pllv3_wait_lock to sleep. See also:
 commit fc8726a2 ("clk: core: support clocks which requires parents
 enable (part 2)")."

imx7s-warp does not even use the FEC interface, so we should not really
configure the parent of IMX7D_ENET_AXI_ROOT_SRC in the common MX7 clock
driver code.

The dts file should use the assigned-clocks/assigned-clock-parents method,
so simply remove the configuration of IMX7D_ENET_AXI_ROOT_SRC parent.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>