msm: mdss: Add SMP per pipe parameter into hw capabilites

Additional SMP parameter 'smp_mb_per_pipe' is required by
userspace as part of hardware capability made available
through sysfs node.

Pipes availablity for a use case can be computed taking these
values, based on which, composition decisions can be made.

Change-Id: I2d790506ca895357762e1eca098ea1734077a097
Signed-off-by: Mayank Chopra <makchopra@codeaurora.org>