msm: display: fb blend setting via MSMFB_METADATA_SET ioctl

MSMFB_METADATA_SET ioctl is added for the fb user to pass
in additional infomation rather than using reserved
fields.
User can set pre-multiplied alpha for the frame buffer via this
ioctl, overlay blend setting will take this into account.

Change-Id: Ic2f6236d84691fb03174ec479874c6928489ea30
Signed-off-by: Ken Zhang <kenz@codeaurora.org>

Conflicts:
	drivers/video/msm/mdp4.h
delos3geur: add branch.sh, extra help

Change-Id: I521bf88d7351a5a2e969ede4a7c3dcb47b7d2c55