fb: fix warning: no return statement in function returning non-void

Warning is reproducible with selected FB_CFB_REV_PIXELS_IN_BYTE.

  CC      drivers/video/sysfillrect.o
In file included from drivers/video/sysfillrect.c:18:
drivers/video/fb_draw.h: In function `fb_rev_pixels_in_long':
drivers/video/fb_draw.h:94: warning: no return statement in function returning non-void
  CC      drivers/video/syscopyarea.o
In file included from drivers/video/syscopyarea.c:22:
drivers/video/fb_draw.h: In function `fb_rev_pixels_in_long':
drivers/video/fb_draw.h:94: warning: no return statement in function returning non-void

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/fb_draw.h

@@ -91,6 +91,7 @@ static inline unsigned long fb_rev_pixels_in_long(unsigned long val,
 		val = comp(val >> 2, val << 2, REV_PIXELS_MASK2);
 	if (bswapmask & 3)
 		val = comp(val >> 4, val << 4, REV_PIXELS_MASK4);
+	return val;
 }
 
 static inline u32 fb_shifted_pixels_mask_u32(u32 index, u32 bswapmask)