drm: Adjust whitespace for legibility

Add a bit of whitespace here and there to make the code look a bit
more structured.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180322152313.6561-7-ville.syrjala@linux.intel.com


Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>