kvargs: fix strcmp helper documentation
kvargs: fix strcmp helper documentation

Minor error, "unless" was used instead of "unlike".

Fixes: a3b85476c51e ("kvargs: add generic string matching callback")
Cc: stable@dpdk.org

Signed-off-by: Gaetan Rivet <5349a78fb7b717c3a3b30d04e535485ef35093c6@u256.net>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk