USB: ehci-msm2: Disable irq to avoid race with resume

If normal interrupt comes immediately after clocks on and before
clearing lpm flag in resume, there are chances that interrupt is
disabled and not enabled again. This leads to USB functionality
failure. Hence disable irq line till resume is completed to resolve
the issue.

CRs-Fixed: 525048
Change-Id: If4fa7aea0e195f01e2d8df5f82fde8568fef9cae
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>