[][Add macsec HW offload backport from kernel 5.18]

[Description]
Add macsec HW offload backport from kernel 5.18.

[Release-log]
N/A

Change-Id: I5b143fe620ec4bcae4075d1d85db5e41c8d48717
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5981730
diff --git a/target/linux/mediatek/patches-5.4/999-1766-02-v5.18-net-add-a-reference-to-MACsec-ops-in-net_device.patch b/target/linux/mediatek/patches-5.4/999-1766-02-v5.18-net-add-a-reference-to-MACsec-ops-in-net_device.patch
new file mode 100644
index 0000000..c3372fd
--- /dev/null
+++ b/target/linux/mediatek/patches-5.4/999-1766-02-v5.18-net-add-a-reference-to-MACsec-ops-in-net_device.patch
@@ -0,0 +1,49 @@
+From 30e9bb8472f4454d0544020574bb03d96ffa0e52 Mon Sep 17 00:00:00 2001
+From: Antoine Tenart <antoine.tenart@bootlin.com>
+Date: Wed, 25 Mar 2020 15:52:31 +0300
+Subject: net: add a reference to MACsec ops in net_device
+
+This patch adds a reference to MACsec ops to the net_device structure,
+allowing net device drivers to implement offloading operations for
+MACsec.
+
+Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
+Signed-off-by: Mark Starovoytov <mstarovoitov@marvell.com>
+Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ include/linux/netdevice.h | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+--- a/include/linux/netdevice.h
++++ b/include/linux/netdevice.h
+@@ -53,6 +53,8 @@ struct netpoll_info;
+ struct device;
+ struct phy_device;
+ struct dsa_port;
++struct macsec_context;
++struct macsec_ops;
+ 
+ struct sfp_bus;
+ /* 802.11 specific */
+@@ -1805,6 +1807,8 @@ enum netdev_ml_priv_type {
+  *
+  *	@threaded:	napi threaded mode is enabled
+  *
++ *	@macsec_ops:    MACsec offloading ops
++ *
+  *	FIXME: cleanup struct net_device such that network protocol info
+  *	moves out.
+  */
+@@ -2109,6 +2113,11 @@ struct net_device {
+ 	bool			proto_down;
+ 	unsigned		wol_enabled:1;
+ 	unsigned		threaded:1;
++
++#if IS_ENABLED(CONFIG_MACSEC)
++	/* MACsec management functions */
++	const struct macsec_ops *macsec_ops;
++#endif
+ };
+ #define to_net_dev(d) container_of(d, struct net_device, dev)
+