Remove unused client greeting_umb

Remove an old client info field from the unmount barrier mechanism which
was removed a while ago.  It used to be compared to a super field to
decide to finish unmount without reconnecting but now we check for our
mounted_client item in the server's btree.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/client.c

@@ -49,7 +49,6 @@ struct client_info {
 	struct delayed_work connect_dwork;
 
 	u64 server_term;
-	u64 greeting_umb;
 
 	bool sending_farewell;
 	int farewell_error;