kernel: add linux 4.9 support

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Tim Harvey <tharvey@gateworks.com> [fixes]

target/linux/generic/patches-4.9/921-always-create-console-node-in-initramfs.patch

@@ -0,0 +1,30 @@
+--- a/scripts/gen_initramfs_list.sh
++++ b/scripts/gen_initramfs_list.sh
+@@ -59,6 +59,18 @@ default_initramfs() {
+ 	EOF
+ }
+ 
++list_openwrt_initramfs() {
++	:
++}
++
++openwrt_initramfs() {
++	# make sure that /dev/console exists
++	cat <<-EOF >> ${output}
++		dir /dev 0755 0 0
++		nod /dev/console 0600 0 0 c 5 1
++	EOF
++}
++
+ filetype() {
+ 	local argv1="$1"
+ 
+@@ -180,6 +192,8 @@ dir_filelist() {
+ 	if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
+ 		${dep_list}print_mtime "$1"
+ 
++		${dep_list}openwrt_initramfs
++
+ 		echo "${dirlist}" | \
+ 		while read x; do
+ 			${dep_list}parse ${x}