msm: kgsl: fix division results for UBSAN warnings

Possible divide by zero can occur in wait_active_percent
calculation as reported by UBSAN. Fix this possible
division by zero.

Change-Id: I9068fbcc9347eade8a51c7fc3526491511188f03
Signed-off-by: Pranav Patel <quic_pranavp@quicinc.com>