android: make persistent_ram based drivers depend on HAVE_MEMBLOCK

m68k doesn't have memblock_reserve, which causes a build failure
with allmodconfig.  Make PERSISTENT_RAM and RAM_CONSOLE depend on
HAVE_MEMBLOCK.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>