drm: Remove useless else block

All prior conditional blocks return from the function, so the else block
can be at the top level of the function.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --cc drivers/gpu/drm/drm_crtc.c
Simple merge