response_get_{string,u64} include error handling for argument resp being
NULL but response_get_token does not handle this.

Make all three of response_get_{string,u64,token} handle NULL resp in
the same way.

Co-authored-by: Jonas Rabenstein [off-list ref]
Signed-off-by: David Kozub <redacted>
Signed-off-by: Jonas Rabenstein <redacted>
---
 block/sed-opal.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/sed-opal.c b/block/sed-opal.c
index e29cb2f445ff..537cd73ea88a 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c

@@ -702,6 +702,11 @@ static const struct opal_resp_tok *response_get_token(
 {
 	const struct opal_resp_tok *tok;
 
+	if (!resp) {
+		pr_debug("Response is NULL\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	if (n >= resp->num) {
 		pr_debug("Token number doesn't exist: %d, resp: %d\n",
 			 n, resp->num);

-- 
2.20.1