zcache & zram: remove x86 dependency from kconfig

Conflicts:
	drivers/staging/zcache/Kconfig
	drivers/staging/zram/Kconfig
zcache-main.c: use MACRO define instead of hardcoded default of lzo

Signed-off-by: Paul Reioux <reioux@gmail.com>
zcache-main: switch to lz4 as default

Signed-off-by: Paul Reioux <reioux@gmail.com>