media: dvbdev: handle ENOMEM error at dvb_module_probe()

If allocation of struct board_info fails, return NULL from
dvb_module_probe().

Fix this warning:
	drivers/media/dvb-core/dvbdev.c:958 dvb_module_probe() error: potential null dereference 'board_info'.  (kzalloc returns null)
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/dvb-core/dvbdev.c

@@ -953,6 +953,8 @@ struct i2c_client *dvb_module_probe(const char *module_name,
 	struct i2c_board_info *board_info;
 
 	board_info = kzalloc(sizeof(*board_info), GFP_KERNEL);
+	if (!board_info)
+		return NULL;
 
 	if (name)
 		strlcpy(board_info->type, name, I2C_NAME_SIZE);