V4L/DVB: gspca - main: Fix a compilation warning

Reported-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/gspca.c

@@ -1467,7 +1467,8 @@ static int vidioc_reqbufs(struct file *file, void *priv,
 	struct gspca_dev *gspca_dev = priv;
 	int i, ret = 0, streaming;
 
-	switch (rb->memory) {
+	i = rb->memory;			/* (avoid compilation warning) */
+	switch (i) {
 	case GSPCA_MEMORY_READ:			/* (internal call) */
 	case V4L2_MEMORY_MMAP:
 	case V4L2_MEMORY_USERPTR: