ehci-msm2: Add support to disable selective suspend

Out of band resume cannot be used when selective suspend
is enabled as hub driver can resume/suspend the port. Add
support to disable selective suspend on platforms which
does not support usual in-band resume signalling.

Change-Id: I1ec604325fd7fd33a0eb7e80eb7d2b1d7b10189b
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>