fsl-diu-fb: drop dead ioctl define

The fsl-diu-fb driver no longer uses this define, and we have a common one
to cover this already (FBIO_WAITFORVSYNC).
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

include/linux/fsl-diu-fb.h

@@ -54,7 +54,6 @@ struct aoi_display_offset {
 };
 
 #define MFB_SET_CHROMA_KEY	_IOW('M', 1, struct mfb_chroma_key)
-#define MFB_WAIT_FOR_VSYNC	_IOW('F', 0x20, u_int32_t)
 #define MFB_SET_BRIGHTNESS	_IOW('M', 3, __u8)
 
 #define MFB_SET_ALPHA		0x80014d00