kernel: add linux 4.4 support

Based on 4.4-rc3. Runtime tested on MIPS.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 47701

target/linux/generic/patches-4.4/000-keep_initrafs_the_default.patch

@@ -0,0 +1,25 @@
+Upstream changed the default rootfs to tmpfs when none has been passed
+to the kernel - this doesn't fit our purposes, so change it back.
+
+Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
+
+--- a/init/do_mounts.c
++++ b/init/do_mounts.c
+@@ -633,6 +633,7 @@ int __init init_rootfs(void)
+ 	if (err)
+ 		return err;
+ 
++#if 0
+ 	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
+ 		(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
+ 		err = shmem_init();
+@@ -640,6 +641,9 @@ int __init init_rootfs(void)
+ 	} else {
+ 		err = init_ramfs_fs();
+ 	}
++#else
++	err = init_ramfs_fs();
++#endif
+ 
+ 	if (err)
+ 		unregister_filesystem(&rootfs_fs_type);