On the OMAP AM3517 platform the uart4_ick gets registered
twice, causing any power management to /dev/ttyO3 to fail
when trying to wake the device up.
This solves the following oops:
[] Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa09e008
[] PC is at serial_omap_pm+0x48/0x15c
[] LR is at _raw_spin_unlock_irqrestore+0x30/0x5c