usb: dwc3: otg: Avoid race condition between gadget start and PHY RESUME

USB cable connection event can race with android gadget register routine
causing pm usage count to zero. This will keep controller driver in
suspend (clocks off) and will result in NULL pointer exception when
android-gadget tries to enumerate using pull-up. Avoid this race by simply
incrementing the pm usage count in case of usb cable connection phy
resume event.

CRs-fixed: 678197
Change-Id: Iaf4154918905e17b2df421c356abb3e3364c9cb9
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>