zsmalloc: Fix "map_vm_area" undefined reference errors.
zsmalloc: Fix "map_vm_area" undefined reference errors.

This patch adds a MMU dependency to configure the ZSMALLOC in
drivers/staging/zsmalloc/Kconfig. Without this patch, build
system can lead to build failure. This was observed during
randconfig testing, in which ZSMALLOC was enabled w/o MMU being
enabled. Following was the error:

LD      vmlinux
drivers/built-in.o: In function `__zs_map_object':
drivers/staging/zsmalloc/zsmalloc-main.c:650: undefined reference to `map_vm_area'
make: *** [vmlinux] Error 1

Signed-off-by: Manjunath Goudar <03794c1cdbe8e6f48e359fe32b07ba9daa6eefe7@gmail.com>
Cc: Nitin Gupta <cc4fec8a34766005dd45d48be045c08d736c11ed@vflare.org>
Cc: Seth Jennings <527af9e7c640877508ac9f4ddd8647c066bca6c6@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>
Cc: Minchan Kim <eee62f459f15dcddf87a8df69e8328e2a2562028@kernel.org>
Cc: Joerg Roedel <4688a6871ff025801033b3c4b039d55a29f8f937@8bytes.org>
Cc: 21a6cafaf0e9b0080692d699c1538d0dfa42b47a@driverdev.osuosl.org
Cc: 2578944098299abf708b08eff6fcf60565553586@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs