Update OpenWrt, fix and add mvebu 5.14 support

patches/ipt-nat6.patch

@@ -0,0 +1,13 @@
+--- a/package/kernel/linux/modules/netfilter.mk	2020-03-20 15:41:58.620893747 +0100
++++ b/package/kernel/linux/modules/netfilter.mk	2020-03-20 15:45:34.389015301 +0100
+@@ -483,7 +483,9 @@
+ define KernelPackage/ipt-nat6
+   TITLE:=IPv6 NAT targets
+   KCONFIG:=$(KCONFIG_IPT_NAT6)
+-  FILES:=$(foreach mod,$(IPT_NAT6-m),$(LINUX_DIR)/net/$(mod).ko)
++  FILES:= \
++	$(LINUX_DIR)/net/ipv6/netfilter/ip6t_NPT.ko \
++	$(LINUX_DIR)/net/ipv6/netfilter/ip6table_nat.ko
+   AUTOLOAD:=$(call AutoLoad,43,$(notdir $(IPT_NAT6-m)))
+   $(call AddDepends/ipt,+kmod-nf-nat6)
+   $(call AddDepends/ipt,+kmod-ipt-conntrack)

patches/smsc75xx.patch

@@ -0,0 +1,26 @@
+Index: package/kernel/linux/modules/usb.mk
+===================================================================
+--- a/package/kernel/linux/modules/usb.mk	(revisione 42462)
++++ b/package/kernel/linux/modules/usb.mk	(copia locale)
+@@ -1091,8 +1091,21 @@
+ endef
+ 
+ $(eval $(call KernelPackage,usb-net-smsc95xx))
++
++define KernelPackage/usb-net-smsc75xx
++  TITLE:=SMSC LAN75XX based USB 2.0 Gigabit ethernet devices
++  KCONFIG:=CONFIG_USB_NET_SMSC75XX
++  FILES:=$(LINUX_DIR)/drivers/$(USBNET_DIR)/smsc75xx.ko
++  AUTOLOAD:=$(call AutoProbe,smsc75xx)
++  $(call AddDepends/usb-net, +kmod-lib-crc16)
++endef
+ 
++define KernelPackage/usb-net-smsc75xx/description
++ Kernel module for SMSC LAN75XX based devices
++endef
+ 
++$(eval $(call KernelPackage,usb-net-smsc75xx))
++
+ define KernelPackage/usb-net-dm9601-ether
+   TITLE:=Support for DM9601 ethernet connections
+   KCONFIG:=CONFIG_USB_NET_DM9601