ARM: dts: msm: Tune SMP block restriction for 8x26

To maximize availability of pipes for both 1080p and 1200p based
8x26 targets, reduce SMP block restriction from 4 to 3.

Change-Id: Ibb5a9d0016ea0d44b152d9c74d9f3a5cbd2acbd3
Signed-off-by: Mayank Chopra <makchopra@codeaurora.org>