mptcp: add the mibs for MP_PRIO

This patch added the mibs for MP_PRIO, MPTCP_MIB_MPPRIOTX for transmitting
of the MP_PRIO suboption, and MPTCP_MIB_MPPRIORX for receiving of it.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index 47bcecc..63914a5 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -24,6 +24,8 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_ECHOADD,		/* Received ADD_ADDR with echo-flag=1 */
 	MPTCP_MIB_RMADDR,		/* Received RM_ADDR */
 	MPTCP_MIB_RMSUBFLOW,		/* Remove a subflow */
+	MPTCP_MIB_MPPRIOTX,		/* Transmit a MP_PRIO */
+	MPTCP_MIB_MPPRIORX,		/* Received a MP_PRIO */
 	__MPTCP_MIB_MAX
 };