usb: ehci-msm2: Fix HUB resume issue upon runtime resume

When the micro a cable is connected over hub, hub is auto suspended
and usb entered into low power mode. If usb device is connected to
the suspended hub then root hub is resumed, it doesn't handle the
device resume for received USB asynchronous interrupt as a result
connected devices are not resumed. To fix this, drive resume
signaling to wakeup peripherals.

CRs-Fixed: 837198
Change-Id: Ic9178e289178f33c0d0a73cec70e5a52686da6e7
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>