drm/msm: suspend devfreq on init

Devfreq turns on and starts recommending power level as soon as it is
initialized. The GPU is still not powered on by the time the devfreq
init happens and this leads to problems on GPU's where register access
is needed to get/set power levels. So we start suspended and only restart
devfreq when GPU is powered on.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>