package/util-linux: make wipefs depend on BR2_USE_MMU
It depends on libblkid and libsmartcols, which use fork().
Fixes:
http://autobuild.buildroot.net/results/82f9712bc90377c625caeb5b175e83a03d5b9d75/
Signed-off-by: Carlos Santos <unixmania@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>