drm/i915: Check framebuffer stride more thoroughly

Make sure the the framebuffer stride is smaller than 32k. That
seems to be the limit on recent hardware. Not quite sure if
<=Gen4 has smaller limits.

Also when using a tiled memory make sure the object stride matches
the framebuffer stride.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>