USB: msm_otg: Don't ignore initial VBUS event

OTG state machine will wait until initial VBUS state is determined.  The
current code ignores the VBUS event when ID is grounded.  If target is
booted with Micro-A cable, the initial VBUS state event is ignored and
state machine is stuck in UNDEFINED state.

CRs-Fixed: 426118
Change-Id: I8a4e32e57ddc09a0adcd62bfd7ec271f7760e6ca
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>