bzip2/lzma: move CONFIG_RD_* options under CONFIG_EMBEDDED

Impact: reduce Kconfig noise

Move the options that control possible initramfs/initrd compressions
underneath CONFIG_EMBEDDED.  The only impact of leaving these options
set to y is additional code in the init section of the kernel; there
is no reason to burden non-embedded users with these options.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>