media: rca: declare formats var as static

As warned:
	drivers/media/platform/rockchip/rga/rga.c:210:16: warning: symbol 'formats' was not declared. Should it be static?
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/rockchip/rga/rga.c

@@ -207,7 +207,7 @@ static int rga_setup_ctrls(struct rga_ctx *ctx)
 	return 0;
 }
 
-struct rga_fmt formats[] = {
+static struct rga_fmt formats[] = {
 	{
 		.fourcc = V4L2_PIX_FMT_ARGB32,
 		.color_swap = RGA_COLOR_RB_SWAP,