compositor-drm: fix drm_waitvblank_pipe() decl style

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor-drm.c b/src/compositor-drm.c
index f24fa0b..66eb5d7 100644
--- a/src/compositor-drm.c
+++ b/src/compositor-drm.c
@@ -610,7 +610,8 @@
  * multi-gpu situation and we need to calculate the vblank sync
  * using DRM_BLANK_HIGH_CRTC_MASK.
  */
-static unsigned int drm_waitvblank_pipe(struct drm_output *output)
+static unsigned int
+drm_waitvblank_pipe(struct drm_output *output)
 {
 	if (output->pipe > 1)
 		return (output->pipe << DRM_VBLANK_HIGH_CRTC_SHIFT) &