ARM: dts: msm: Define power configuration for msm8996 and msm8998

Power configuration is a value measured as HxW of a video
session. If the resolution of current video session meets
this value, the session will be configured in low power
mode to get power benefits.

CRs-Fixed: 1106972

Change-Id: Ibe4eba7a76a070b1bc02caff89cfb871993043c2
Signed-off-by: Vikash Garodia <vgarodia@codeaurora.org>