cifs: remove two cases where rc is set unnecessarily in sid_to_id

In both these cases sid_to_id unconditionally returned success, and
used the default uid/gid for the mount, so setting rc is confusing
and simply gets overwritten (set to 0) later in the function.

Addresses-Coverity: 1491672 ("Unused value")
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsacl.c

@@ -397,7 +397,6 @@ try_upcall_to_get_id:
 	saved_cred = override_creds(root_cred);
 	sidkey = request_key(&cifs_idmap_key_type, sidstr, "");
 	if (IS_ERR(sidkey)) {
-		rc = -EINVAL;
 		cifs_dbg(FYI, "%s: Can't map SID %s to a %cid\n",
 			 __func__, sidstr, sidtype == SIDOWNER ? 'u' : 'g');
 		goto out_revert_creds;
@@ -410,7 +409,6 @@ try_upcall_to_get_id:
 	 */
 	BUILD_BUG_ON(sizeof(uid_t) != sizeof(gid_t));
 	if (sidkey->datalen != sizeof(uid_t)) {
-		rc = -EIO;
 		cifs_dbg(FYI, "%s: Downcall contained malformed key (datalen=%hu)\n",
 			 __func__, sidkey->datalen);
 		key_invalidate(sidkey);