usb: msm_otg: disallow suspend during charging detection

A cable connection could occur as the device is just about to
enter systemwide suspend. This interrupt will kick off the
charging detection algorithm, but the controller could become
suspended and may lead to ULPI timeouts when the PHY is later
resumed. Note that prior to starting charger detection, the
B-session valid state bit is asserted. We can then fix this in
the general case by preventing the controller from suspending
if B_SESS_VLD is set and the bus is not suspended.

Change-Id: Ie4c8cc2eccad77c8e77e4765c0a8ec3dfd773953
CRs-Fixed: 386262
Signed-off-by: Jack Pham <jackp@codeaurora.org>