fs: dlm: fix typo in tlv prefix

This patch fixes a small typo in a unused struct field. It should named
be t_pad instead of o_pad. Came over this as I updated wireshark
dissector.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/dlm_internal.h

@@ -468,7 +468,7 @@ struct dlm_rcom {
 struct dlm_opt_header {
 	uint16_t	t_type;
 	uint16_t	t_length;
-	uint32_t	o_pad;
+	uint32_t	t_pad;
 	/* need to be 8 byte aligned */
 	char		t_value[];
 };