msm: mdss: add mdss support for msm8937

Initial set of changes to support msm8937. This includes
adding MDP HW version for msm8937, and some makefile
changes.

Change-Id: I0646ea76060696d4fe35e3f6f5f2a949474c0b8b
Signed-off-by: Krishna Chaitanya Devarakonda <kdevarak@codeaurora.org>