msm: mdss: add mdp overlap and prefill bandwidth calculations

This patch implements a set of new equations proposed by h/w team to
calculate mdp bandwidth. MDP has bandwidth requests during both
blanking and active periods. During blanking area, mdp needs to fill
its internal buffers, such as latency buffer, outstanding buffer,
pingpong buffer, etc. This bandwidth is called prefill bandwidth and
it is determined by the total amount of bytes of buffers to be filled
and the total amount of blanking time available. The bandwidth for the
active peroid is called overlap bandwidth which is the max bandwidth
request of all overlapped regions. The final vote from mdp would be
the worst case of prefill bandwidth and overlap bandwidth.

Change-Id: Ib83caf6a3e15c33a2cd71d14e8413b1d9049de29
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>