msm: mdss: Increase max BW cap for low kbps to 2.75G

Increase the bandwidth cap for low kpbs to 2.75G to support. This allows
the following use case to go through MDP:
* 2xRGBX_8888 full screen layer WQXGA resolution
* 1xRGB_888 full screen layer WQXGA resolution

But still fail other use cases that could lead to underrun.

Change-Id: I826b014d663ff69c1611e9463088ba712f40efc8
Signed-off-by: Ramkumar Radhakrishnan <ramkumar@codeaurora.org>
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>