msm:rq_stats: Fix hotplug attribute during the suspend failure

If the system suspend fails, the hotplug_disable attribute remains
set. This prevents any change to core status from mpdecision. Reset
the value of this attribute if the module receives PM_POST_RESTORE
notification.

Change-Id: I22fd639134adbeb8f8f96603e285151480f537ec
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>