msm: timer: read timer twice on 8960

There is an issue with the KPSS where sometimes timer reads can be
corrupted if done while the timer is updating. Fix this by reading
twice, and ensuring successive reads are at most one tick apart.

Change-Id: I12e6289b472c2129dba7063ca9facdbfa577bcc9
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>