Revert "drm: Add and handle new aspect ratios in DRM layer"

This reverts commit a68362fe.

Adding new mode flags willy nilly breaks existing userspace. We need to
coordinate this better, potentially with a new client cap that only
exposes the aspect ratio flags when userspace is prepared for them
(similar to what we do with stereo 3D modes).

Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: Lin, Jia <lin.a.jia@intel.com>
Cc: Akashdeep Sharma <akashdeep.sharma@intel.com>
Cc: Jim Bride <jim.bride@linux.intel.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1478176304-6743-1-git-send-email-ville.syrjala@linux.intel.com