drivers/staging/zcache/zcache-main.c: fix build

flush_dcache_page() takes a page*, not a void*.  It breaks ia64.

Remove this and another unused function.  Warnings remain:

drivers/staging/zcache/zcache-main.c: In function '__check_disable_cleancache':
drivers/staging/zcache/zcache-main.c:1837: warning: return from incompatible pointer type
drivers/staging/zcache/zcache-main.c: In function '__check_disable_frontswap':
drivers/staging/zcache/zcache-main.c:1838: warning: return from incompatible pointer type
drivers/staging/zcache/zcache-main.c: In function '__check_disable_frontswap_ignore_nonactive':
drivers/staging/zcache/zcache-main.c:1842: warning: return from incompatible pointer type

Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>