usb: xhci_msm: Check power event irq status after timeout

When the system has many interrupts need to handle, there is a
race to fail to call mxhci_hsic_pwr_event_irq handler. Prior to
call panic, check for interrupt status after timeout.

Change-Id: Ie26ccfa7315ff1814178248c091c29fafcfb7728
Signed-off-by: Guang Jian Zeng <gzeng@codeaurora.org>