USB: ci13xxx_msm: Clear ULPI_SERIAL_EN for remote wakeup workaround

With ULPI_SERIAL_EN software must ensure that driver sets FPR bit
(for remote wakeup) within 3msec of bringing USB PHY out of suspend.
As this requirement is difficult to meet, clear ULPI_SERIAL_EN as per
the recommendation. Apparently there is no functionality issue due to
this but when the condition happens, remote wakeup signalling might
not be fully as per the specification.

Change-Id: I5423e1f01f523d7321823007c58cc0c02c4aead2
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>