ARM: dts: msm: Update the graphics clock frequencies on msm8996 v2

Update the fmax rates for the graphics clock on msm8996 v2
in the clock and regulator nodes to align with the frequency
plan.

Change-Id: I38d22d225b4c7ef7391b441303a6c1caa612a9b0
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>