bzip2/lzma: fix built-in initramfs vs CONFIG_RD_GZIP

Impact: Resolves build failures in some configurations

Makes it possible to disable CONFIG_RD_GZIP . In that case, the
built-in initramfs will be compressed by whatever compressor is
available (bzip2 or lzma) or left uncompressed if none is available.

It also removes a couple of warnings which occur when no ramdisk
compression at all is chosen.

It also restores the select ZLIB_INFLATE in drivers/block/Kconfig
which somehow came missing. This is needed to activate compilation of
the stuff in zlib_deflate.

Signed-off-by: Alain Knaff <alain@knaff.lu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/usr/initramfs_data.S b/usr/initramfs_data.S
index c2e1ad4..7c6973d 100644
--- a/usr/initramfs_data.S
+++ b/usr/initramfs_data.S
@@ -26,5 +26,5 @@
 */
 
 .section .init.ramfs,"a"
-.incbin "usr/initramfs_data.cpio.gz"
+.incbin "usr/initramfs_data.cpio"