msm: mdss: implement compat ioctl for mdss-fb

Implement an entry point for compat ioctl in mdss
framebuffer driver.
Implement compat ioctls in a new file. All the fb
ioctls that require compat layer translation have
been added here. If the user process is
from a 32-bit world, then the compat ioctl
does an appropriate command conversion to keep the
existing ioctl implementation unchanged.

Signed-off-by: Manoj Rao <manojraj@codeaurora.org>
Change-Id: I24c378116b2504db29ce0b17d690b0e4779426d6