kbuild: remove commented-out INITRD_COMPRESS

This code has been commented out since commit b7000ade
("Don't set the INITRD_COMPRESS environment variable automatically").

Clean it up now.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -934,19 +934,6 @@ ifdef CONFIG_MODULE_COMPRESS
 endif # CONFIG_MODULE_COMPRESS
 export mod_compress_cmd
 
-# Select initial ramdisk compression format, default is gzip(1).
-# This shall be used by the dracut(8) tool while creating an initramfs image.
-#
-INITRD_COMPRESS-y                  := gzip
-INITRD_COMPRESS-$(CONFIG_RD_BZIP2) := bzip2
-INITRD_COMPRESS-$(CONFIG_RD_LZMA)  := lzma
-INITRD_COMPRESS-$(CONFIG_RD_XZ)    := xz
-INITRD_COMPRESS-$(CONFIG_RD_LZO)   := lzo
-INITRD_COMPRESS-$(CONFIG_RD_LZ4)   := lz4
-# do not export INITRD_COMPRESS, since we didn't actually
-# choose a sane default compression above.
-# export INITRD_COMPRESS := $(INITRD_COMPRESS-y)
-
 ifdef CONFIG_MODULE_SIG_ALL
 $(eval $(call config_filename,MODULE_SIG_KEY))