drm/crtc: Add property for aspect ratio

Added a property to enable user space to set aspect ratio.
This patch contains declaration of the property and code to create the
property.

v2: Thierry's review comments.
	- Made aspect ratio enum generic instead of HDMI/CEA specfic
	- Removed usage of temporary aspect_ratio variable

v3: Thierry's review comments.
	- Fixed indentation

v4: Thierry's review comments.
	- Return ENOMEM when property creation fails

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>
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index def54f9..a0db2d4a 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -88,6 +88,11 @@
 #define DRM_MODE_SCALE_CENTER		2 /* Centered, no scaling */
 #define DRM_MODE_SCALE_ASPECT		3 /* Full screen, preserve aspect */
 
+/* Picture aspect ratio options */
+#define DRM_MODE_PICTURE_ASPECT_NONE	0
+#define DRM_MODE_PICTURE_ASPECT_4_3	1
+#define DRM_MODE_PICTURE_ASPECT_16_9	2
+
 /* Dithering mode options */
 #define DRM_MODE_DITHERING_OFF	0
 #define DRM_MODE_DITHERING_ON	1