M2: otg: fix runaway wakelock

When booting with wall-charger plugged-in state machine transitions to
STATE_B_PERIPHERAL (B_SESS_VLD bit is set in msm_otg_init_sm).

Aftr uplugging, bit is not cleared, and state machine never transitions
to IDLE, consequently msm_otg wakelock is never unlocked.
Enable RTC write

Change-Id: I462458c9147ec663115b807fa4df979977796b2d