[media] drx-j: don't use mc_info before checking if its not NULL

smatch warning:
	drivers/media/dvb-frontends/drx39xyj/drxj.c:20803 drx_ctrl_u_code() warn: variable dereferenced before check 'mc_info' (see line 20800)

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/dvb-frontends/drx39xyj/drxj.c

@@ -20208,12 +20208,14 @@ static int drx_ctrl_u_code(struct drx_demod_instance *demod,
 	const u8 *mc_data_init = NULL;
 	u8 *mc_data = NULL;
 	unsigned size;
-	char *mc_file = mc_info->mc_file;
+	char *mc_file;
 
 	/* Check arguments */
-	if (!mc_info || !mc_file)
+	if (!mc_info || !mc_info->mc_file)
 		return -EINVAL;
 
+	mc_file = mc_info->mc_file;
+
 	if (!demod->firmware) {
 		const struct firmware *fw = NULL;