net/enic: re-enable link status change interrupt

net/enic: re-enable link status change interrupt

When INTx is used, the interrupt handler needs to explicitly re-enable
interrupt in order to receive another one in future. The LSC interrupt
handler currently does not, and the link state never gets updated when
INTx is used (e.g. uio_pci_generic). Call rte_intr_ack() at the end of
the handler, to re-enable INTx.

Fixes: fefed3d1e62c ("enic: new driver")
Cc: stable@dpdk.org
Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>