drm/msm/dsi-staging: use parser APIs for custom panel data

In case custom panel data is used instead of device tree,
parse the data using parser sub-module and use its APIs instead
of device tree.

CRs-Fixed: 2223812
Change-Id: Id7d69d2ed35526e0c0e8e92739c85b9e22f4ab32
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>