initramfs: move gen_initramfs_list.sh from scripts/ to usr/

scripts/gen_initramfs_list.sh is only invoked from usr/Makefile.
Move it so that all tools to create initramfs are self-contained
in the usr/ directory.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Documentation/early-userspace/README

@@ -66,17 +66,17 @@ early userspace image can be built by an unprivileged user.
 
 As a technical note, when directories and files are specified, the
 entire CONFIG_INITRAMFS_SOURCE is passed to
-scripts/gen_initramfs_list.sh.  This means that CONFIG_INITRAMFS_SOURCE
+usr/gen_initramfs_list.sh.  This means that CONFIG_INITRAMFS_SOURCE
 can really be interpreted as any legal argument to
 gen_initramfs_list.sh.  If a directory is specified as an argument then
 the contents are scanned, uid/gid translation is performed, and
 usr/gen_init_cpio file directives are output.  If a directory is
-specified as an argument to scripts/gen_initramfs_list.sh then the
+specified as an argument to usr/gen_initramfs_list.sh then the
 contents of the file are simply copied to the output.  All of the output
 directives from directory scanning and file contents copying are
 processed by usr/gen_init_cpio.
 
-See also 'scripts/gen_initramfs_list.sh -h'.
+See also 'usr/gen_initramfs_list.sh -h'.
 
 Where's this all leading?
 =========================

Documentation/filesystems/ramfs-rootfs-initramfs.txt

@@ -164,7 +164,7 @@ Documentation/early-userspace/README for more details.)
 The kernel does not depend on external cpio tools.  If you specify a
 directory instead of a configuration file, the kernel's build infrastructure
 creates a configuration file from that directory (usr/Makefile calls
-scripts/gen_initramfs_list.sh), and proceeds to package up that directory
+usr/gen_initramfs_list.sh), and proceeds to package up that directory
 using the config file (by feeding it to usr/gen_init_cpio, which is created
 from usr/gen_init_cpio.c).  The kernel's build-time cpio creation code is
 entirely self-contained, and the kernel's boot-time extractor is also

usr/Makefile

@@ -24,7 +24,7 @@ $(obj)/initramfs_data.o: $(obj)/$(datafile_y) FORCE
 # Generate the initramfs cpio archive
 
 hostprogs-y := gen_init_cpio
-initramfs   := $(CONFIG_SHELL) $(srctree)/scripts/gen_initramfs_list.sh
+initramfs   := $(CONFIG_SHELL) $(srctree)/$(src)/gen_initramfs_list.sh
 ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)), \
 			$(shell echo $(CONFIG_INITRAMFS_SOURCE)),-d)
 ramfs-args  := \