[media] atmel-isi: get rid of a warning

drivers/media/platform/soc_camera/atmel-isi.c: In function 'start_streaming':
drivers/media/platform/soc_camera/atmel-isi.c:387:6: warning: variable 'sr' set but not used [-Wunused-but-set-variable]
  u32 sr = 0;
      ^

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
diff --git a/drivers/media/platform/soc_camera/atmel-isi.c b/drivers/media/platform/soc_camera/atmel-isi.c
index 96a4b11..c5291b0 100644
--- a/drivers/media/platform/soc_camera/atmel-isi.c
+++ b/drivers/media/platform/soc_camera/atmel-isi.c
@@ -384,7 +384,6 @@
 	struct soc_camera_device *icd = soc_camera_from_vb2q(vq);
 	struct soc_camera_host *ici = to_soc_camera_host(icd->parent);
 	struct atmel_isi *isi = ici->priv;
-	u32 sr = 0;
 	int ret;
 
 	/* Reset ISI */
@@ -398,7 +397,7 @@
 
 	spin_lock_irq(&isi->lock);
 	/* Clear any pending interrupt */
-	sr = isi_readl(isi, ISI_STATUS);
+	isi_readl(isi, ISI_STATUS);
 
 	if (count)
 		start_dma(isi, isi->active);