ARM: dts: msm: override initial pwrlevel for MSM8996ProAU

Current DRM driver set GPU clock rate with initial pwrlevel and use it
all the time. This value is too low and couldn't cover many computing
tasks. Change to a higher value for automotive system.

Change-Id: I348f187bfb8c0c2a3936a132bc0142fd5553226c
Signed-off-by: Kasin Li <donglil@codeaurora.org>