usb: dwc3-msm: Fix pwr_event_irq for host mode

During host bus suspend, the resuming interrupt could be generated
from both pwr_event and hs_phy IRQ sources, in which case
they would both attempt to request the controller to exit low power
mode, causing a runtime PM counter mismatch. Fix this by simply
making the hs_phy_irq handler defer to the pwr_event_irq handlers
to perform the resume, and make the latter call dwc3_resume_work()
directly, which can handle both device and host resume.

For pwr_event_irq, also move its processing of the PWR_EVENT_IRQ_STAT
register to pwr_event_handler() which only executes when the
controller's clocks are on. Add additional checks to ensure P3 and
L2 statuses are accounted for, and ensure the masks are enabled for
IN/OUT events prior to their possible transitions.

Change-Id: Ia23f8b2247a4a4036de42260116779954733dfa2
Signed-off-by: Jack Pham <jackp@codeaurora.org>