initramfs: select builtin initram compression algorithm on KConfig instead of Makefile

initramfs: select builtin initram compression algorithm on KConfig instead of Makefile

Move the current builtin initram compression algorithm selection from
the Makefile into the INITRAMFS_COMPRESSION variable.  This makes
deciding algorithm precedence easier and would allow for overrides if
new algorithms want to be tested.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <[email protected]>
Cc: P J P <[email protected]>
Cc: Paul Bolle <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>