msm: mdss: Add support for command mode autorefresh

This change adds support to autorefresh the command mode panels
without having to manually issue a kickoff. We need to enable
sys/class/graphics/fb0/msm_cmd_autorefresh_en to configure after
how many idle ticks(read ptr/vsync) should we trigger a frame.

e.g. If we want to send an update at 60fps
we need to echo 1 > sys/class/graphics/fb0/msm_cmd_autorefresh_en

to disable we need to echo 0 >
	sys/class/graphics/fb0/msm_cmd_autorefresh_en

Change-Id: Ib0cda1142f8fadfa6cad5e61e0c7fb36fe43aca1
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>