usb: dwc3-msm: Add support for 2nd set of wakeup IRQs

Certain targets may have a dual port capable host controller.
Add support for the PHY IRQs for the second port. Since the SSPHY
autosuspend will be disabled for such controllers, remove the
support of pwr_evnt_irq as a mandatory IRQ and allow SSPHY to go
into P3 as a part of suspend sequence. Handle the logic
gracefully to maintain single port controllers.

Change-Id: I5a53d6e23f64bec7ae940d23923df310309a28da
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>