kbuild: rename hostprogs-y/always to hostprogs/always-y

In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.

It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.

This commit renames like follows:

  always       ->  always-y
  hostprogs-y  ->  hostprogs

So, scripts/Makefile will look like this:

  always-$(CONFIG_BUILD_BIN2C) += ...
  always-$(CONFIG_KALLSYMS)    += ...
      ...
  hostprogs := $(always-y) $(always-m)

I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.

The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
diff --git a/usr/Makefile b/usr/Makefile
index 244862b..18aed2a 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -52,7 +52,7 @@
 
 cpio-data := $(obj)/initramfs_data.cpio
 
-hostprogs-y := gen_init_cpio
+hostprogs := gen_init_cpio
 
 # .initramfs_data.cpio.d is used to identify all files included
 # in initramfs and to detect if any files are added/removed.