usb: gadget: ci13xxx: ensure exit from lpm on software connect/disconnect

In case the USB gadget controller is in low power mode (lpm) due
to bus suspend, the controller may not be accessible, however
the gadget framework still allow software disconnect and connect using the
pullup operation. This may results with a crash when we try to access
the controller.

Therefore we must resume the controller and exit lpm before do any
write/read operations to the controller registers.
Write helper function to accomplish that and use it upon pullup operation.

CRs-Fixed: 550217
Change-Id: I0969cfe39843e50c040abaf5648105a345456e64
Signed-off-by: Ido Shayevitz <idos@codeaurora.org>