msm: pil: Add support for proxy unvoting via SMP2P interrupt

Add support to use an SMP2P interrupt to proxy unvote. Do this
without affecting existing subsystems that may not use SMP2P. If
a subsystem does not use SMP2P, keep current implementation of
performing the unvote 10 seconds after it is brought out of reset.
If the subsystem uses SMP2P to indicate clock/power ready, then
ignore the proxy timeout value and unvote only when the interrupt
occurs. As before, if an error occurs while booting, perform the
unvote immediately after the peripheral is shutdown.

Change-Id: I62b1425cb8a536f455b6e110beabcbd59fdd5479
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>