firmware: meson_sm: fix to avoid potential NULL pointer dereference

of_match_device() may fail and returns a NULL pointer.

Fix this by checking the return value of of_match_device.

Fixes: 8cde3c2153 ("firmware: meson_sm: Rework driver as a proper platform driver")
Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/tencent_AA08AAA6C4F34D53ADCE962E188A879B8206@qq.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

drivers/firmware/meson/meson_sm.c

@@ -292,6 +292,8 @@ static int __init meson_sm_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	chip = of_match_device(meson_sm_ids, dev)->data;
+	if (!chip)
+		return -EINVAL;
 
 	if (chip->cmd_shmem_in_base) {
 		fw->sm_shmem_in_base = meson_sm_map_shmem(chip->cmd_shmem_in_base,