tee: amdtee: fix an IS_ERR() vs NULL bug

The __get_free_pages() function does not return error pointers it returns
NULL so fix this condition to avoid a NULL dereference.

Fixes: 757cc3e9 ("tee: add AMD-TEE driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/amdtee/core.c

@@ -203,9 +203,8 @@ static int copy_ta_binary(struct tee_context *ctx, void *ptr, void **ta,
 
 	*ta_size = roundup(fw->size, PAGE_SIZE);
 	*ta = (void *)__get_free_pages(GFP_KERNEL, get_order(*ta_size));
-	if (IS_ERR(*ta)) {
-		pr_err("%s: get_free_pages failed 0x%llx\n", __func__,
-		       (u64)*ta);
+	if (!*ta) {
+		pr_err("%s: get_free_pages failed\n", __func__);
 		rc = -ENOMEM;
 		goto rel_fw;
 	}