drm: drm_atomic.h: delete duplicated word in comment

Drop doubled word "than" in a comment.

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: [e-mail]
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

include/drm/drm_atomic.h

···
 	 *
 	 * Will be signalled when all hw register changes for this commit have
 	 * been written out. Especially when disabling a pipe this can be much
-	 * later than than @flip_done, since that can signal already when the
+	 * later than @flip_done, since that can signal already when the
 	 * screen goes black, whereas to fully shut down a pipe more register
 	 * I/O is required.
 	 *