memcmp->nv_strncmp conversion, in addition to name change, should have
inverted the return value.
But nv_strncmp does not act like strncmp - it does not check for string
terminator, returns true/false instead of -1/0/1 and has different
parameters order.
Let's rename it to nv_memcmp and let it act like memcmp.
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> Signed-off-by: Ben Skeggs <bskeggs@redhat.com>