msm: cpp: Ignore hardware interrupt when timer expires

Check for validity of timer before processing hardware
Interrupt. Also in case of timeout reset timer variable
so that if interrupt in case is received after timeout can
be ignored to avoid timing issues.

Change-Id: I4a6922327cdf38a2e299d2c1b7977e4dde07a205
Signed-off-by: Shilpa Mamidi <shilpam@codeaurora.org>