msm: mdss: Add atomic commit PP support

This change adds support for SSPP postprocessing using the
atomic commit ioctl. The configuration given as part of the
ioctl will be cached in the same pipe res as before, and the
register programming sequence will be called from the pipe
setup as before.

Change-Id: Ida8209f80e55e9d5009b5df4e55f787b4a85ddc0
Signed-off-by: Benet Clark <benetc@codeaurora.org>