media: imx: shut up a false positive warning

With imx, gcc produces a false positive warning:

	drivers/staging/media/imx/imx-media-csi.c: In function 'csi_idmac_setup_channel':
	drivers/staging/media/imx/imx-media-csi.c:457:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
	   if (passthrough) {
	      ^
	drivers/staging/media/imx/imx-media-csi.c:464:2: note: here
	  default:
	  ^~~~~~~

That's because the regex it uses for fall trough is not
good enough. So, rearrange the fall through comment in a way
that gcc will recognize.
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/staging/media/imx/imx-media-csi.c

@@ -460,7 +460,8 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
 			passthrough_cycles = incc->cycles;
 			break;
 		}
-		/* fallthrough for non-passthrough RGB565 (CSI-2 bus) */
+		/* for non-passthrough RGB565 (CSI-2 bus) */
+		/* Falls through */
 	default:
 		burst_size = (image.pix.width & 0xf) ? 8 : 16;
 		passthrough_bits = 16;