dwc3-msm: Perform soft reset of USB GSI interface

USB GSI wrapper is trying to access previously programmed IPA GSI
channel related doorbell address with USB GSI endpoint on unblocking
USB GSI wrapper with USB composition switch although USB software
hasn't performed ringing doorbell functionality with that particular
USB GSI endpoint. This is causing USB SMMU page fault. Fix this issue
by performing soft reset of USB GSI interface before configuring event
buffer to make sure that USB GSI interface state machine is reset and
doesn't see previous session related stale configuration.

Change-Id: I29cbf3e70e63f6bf71c089d4810f7b01767cb7e7
Signed-off-by: Mayank Rana <mrana@codeaurora.org>