maintainers: update for nfp
maintainers: update for nfp

Release-on-close has been implemented for the NFP PMD. Remove the
UNMAINTAINED flag.

Signed-off-by: Heinrich Kuhn <490a1483038e40779d698db3422f7b34e637e884@netronome.com>
Acked-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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