msm: vidc: avoid crash due to division by zero

There is a crash due to division by zero in a very
corner case while printing statistics when debug logs
are enabled. Avoid the crash by checking for divisor
is non zero before division operation.

Change-Id: Ideaa626303bc7955f41851f068bbd0e19d3c6b90
Signed-off-by: Srinu Gorle <sgorle@codeaurora.org>