remove the old zcache
Update zcache to Linux kernel 3.11

Conflicts:
	drivers/staging/zcache/Kconfig
	drivers/staging/zcache/Makefile
	drivers/staging/zcache/ramster.h
	drivers/staging/zcache/tmem.c
	drivers/staging/zcache/tmem.h
	drivers/staging/zcache/zbud.c
	drivers/staging/zcache/zcache-main.c
	drivers/staging/zcache/zcache.h
Backport zbud from kernel 3.11

Conflicts:
	mm/Kconfig
	mm/Makefile