drm: Handle aspect ratio info in legacy modeset path

drm: Handle aspect ratio info in legacy modeset path

If the user-space does not support aspect-ratio, and requests for a
modeset with mode having aspect ratio bits set, then the given
user-mode must be rejected. Secondly, while preparing a user-mode from
kernel mode, the aspect-ratio info must not be given, if aspect-ratio
is not supported by the user.

This patch:
1. rejects the modes with aspect-ratio info, during modeset, if the
   user does not support aspect ratio.
2. does not load the aspect-ratio info in user-mode structure, if
   aspect ratio is not supported.
3. adds helper functions for determining if aspect-ratio is expected
   in user-mode and for allowing/disallowing the aspect-ratio, if its
   not expected.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
V3: Addressed review comments from Ville:
    Do not corrupt the current crtc state by updating aspect-ratio on
    the fly.
V4: rebase
V5: As suggested by Ville, rejected the modeset calls for modes with
    aspect ratio, if the user does not set aspect-ratio cap.
V6: Used the helper functions for determining if aspect-ratio is
    expected in the user-mode.
V7: rebase
V8: rebase
V9: rebase
V10: Modified the commit-message
V11: rebase
V12: Merged the patch for adding aspect-ratio helper functions
     with this patch.
V13: Minor modifications as suggested by Ville.
V14: Removed helper functions, as they were used only once in legacy
     modeset path, as suggested by Daniel Vetter.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1525777785-9740-8-git-send-email-ankit.k.nautiyal@intel.com