optee: fix kfree NULL pointer

This patch fixes the following Coccinelle error:
drivers/tee/optee/ffa_abi.c: 877: ERROR  optee is NULL but dereferenced.

If memory allocation fails, optee is null pointer. the code will goto err
and release optee.

Fixes: 4615e5a3 ("optee: add FF-A support")
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
[jw: removed the redundant braces]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/ffa_abi.c

@@ -810,10 +810,9 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
 		return -EINVAL;
 
 	optee = kzalloc(sizeof(*optee), GFP_KERNEL);
-	if (!optee) {
-		rc = -ENOMEM;
-		goto err;
-	}
+	if (!optee)
+		return -ENOMEM;
+
 	optee->pool = optee_ffa_config_dyn_shm();
 	if (IS_ERR(optee->pool)) {
 		rc = PTR_ERR(optee->pool);