msm: mdss: allocate SMP blocks for worst case

SMP allocations are not shadowed at vsync, this can mean that any
changes in SMP allocation may cause unexpected behavior such as tearing
in screen. In order to avoid this, reserve enough SMP blocks for the
worst possible configuration expected for UI layers.

Change-Id: I7d50b73e91391d3729907e7353d1d3c8167c5c5d
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>