drm/edid: Check for user aspect ratio input

In case user has specified an input for aspect ratio through the property,
then the user space value for PAR would take preference over the value from
CEA mode list.

v2: Thierry's review comments.
	- Modified the comment "Populate..." as per review comments

v3: Thierry's review comments.
	- Modified the comment to block comment format.

Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>