sdm: Add get brightness node support for dpps

DPPS needs to use brightness node, but this node is hard code in the
previous dpps code, and dpps have to write multi-define hard code for
brightness node in multi-displays. so this patch change the previous
way, dpps can get brightness base path through display information from
sdm.

Change-Id: I1dda840fcd32edd9534968cfd615f87707768ba1
6 files changed