ip6mr: Remove MFC_NOTIFY and refactor flags

MFC_NOTIFY exists in ip6mr, probably as some legacy code
[was already removed for ipmr in commit
06bd6c0370 ("net: ipmr: remove unused MFC_NOTIFY flag and make the flags enum").
Remove it from ip6mr as well, and move the enum into a common file;
Notice MFC_OFFLOAD is currently only used by ipmr.

Signed-off-by: Yuval Mintz <yuvalm@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/mroute_base.h

@@ -45,6 +45,15 @@ struct vif_device {
 
 #define VIF_EXISTS(_mrt, _idx) (!!((_mrt)->vif_table[_idx].dev))
 
+/* mfc_flags:
+ * MFC_STATIC - the entry was added statically (not by a routing daemon)
+ * MFC_OFFLOAD - the entry was offloaded to the hardware
+ */
+enum {
+	MFC_STATIC = BIT(0),
+	MFC_OFFLOAD = BIT(1),
+};
+
 /**
  * struct mr_mfc - common multicast routing entries
  * @mnode: rhashtable list