drm/msm/dsi-staging: add lp11-init support for DRM DSI driver

Some panels have requirement to toggle the reset gpio pin
before sending panel init command. This change provides support
to parse this lp11-init property from panel dtsi file. When there
is power off, lp11-init logic is disabled so that panel off
sequence is not changed.

Change-Id: I1f01b65010a00cba593f94c71dcab134cb1dd758
Signed-off-by: Tharun Raj Soma <tsoma@codeaurora.org>