ARM: msm: Stop counting before reprogramming clockevent

If the clockevent is forcibly reprogrammed to have a different
match value we mistakenly assume the timer is not ticking and
program a new match value while the timer is running. Although we
clear the timer before programming a new match, it's better to
stop the timer before clearing it so that we're sure the proper
amount of ticks are counted. Failure to do so can lead to missed
ticks and system hangs.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>