Return encapsulated Unspecified error

Fix #3455.

Signed-off-by: Steven Bellock <[email protected]>

Author: steven-bellock

library/spdm_requester_lib/libspdm_req_encap_challenge_auth.c

@@ -158,7 +158,9 @@ libspdm_return_t libspdm_get_encap_response_challenge_auth(
     ptr += hash_size;
 
     if (!libspdm_get_random_number(SPDM_NONCE_SIZE, ptr)) {
-        return LIBSPDM_STATUS_LOW_ENTROPY;
+        return libspdm_generate_encap_error_response(
+            context, SPDM_ERROR_CODE_UNSPECIFIED, 0,
+            response_size, response);
     }
     ptr += SPDM_NONCE_SIZE;