drm: add picture aspect ratio flags

This patch adds drm flag bits for aspect ratio information

Currently drm flag bits don't have field for mode's picture
aspect ratio. This field will help the driver to pick mode with
right aspect ratio, and help in setting right VIC field in avi
infoframes.

V2: Addressed review comments from Sean
- Changed PAR-> PIC_AR
V3: Rebase
V3: Added r-b by Jose

Change-Id: I40cd7fc8393166b710a5f1faaea6e7dac59af65b
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Reviewed-by: Jose Abreu <Jose.Abreu@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1476705880-15600-2-git-send-email-shashank.sharma@intel.com
Git-commit: 876f43c073d79ad3f14a4cebd1aea1f39fc4daf5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[nbahrani@codeaurora.org: resolve merge conflicts by changing
 the mask bits to 27:24 instead of 22:19]
Signed-off-by: Navid Bahrani <nbahrani@codeaurora.org>