[media] mx2_camera: get rid of a warning

drivers/media/platform/soc_camera/mx2_camera.c: In function 'mx27_camera_emma_prp_reset':
drivers/media/platform/soc_camera/mx2_camera.c:812:6: warning: variable 'cntl' set but not used [-Wunused-but-set-variable]
  u32 cntl;
      ^
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/platform/soc_camera/mx2_camera.c

@@ -809,10 +809,9 @@ static int mx2_camera_init_videobuf(struct vb2_queue *q,
 
 static int mx27_camera_emma_prp_reset(struct mx2_camera_dev *pcdev)
 {
-	u32 cntl;
 	int count = 0;
 
-	cntl = readl(pcdev->base_emma + PRP_CNTL);
+	readl(pcdev->base_emma + PRP_CNTL);
 	writel(PRP_CNTL_SWRST, pcdev->base_emma + PRP_CNTL);
 	while (count++ < 100) {
 		if (!(readl(pcdev->base_emma + PRP_CNTL) & PRP_CNTL_SWRST))