msm: mdss: Add support to select max MDP bandwidth

MDSS currently has fixed maximum bandwidth enabled in DT file.
But there are scenarios where this maximum bandwidth support
can change to enhance performance. Based on scenarios such as
camera use, or flip involved declare the max bandwidth for
usecase in DT and change accordingly based on the usecase.

Change-Id: Icc85d75d7a60fe6f934a1fbd9d5077b620b2993d
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>