liquidio: moved liquidio_napi_poll to lio_core.c

Moving common liquidio_napi_poll to lio_core.c

Signed-off-by: Intiyaz Basha <intiyaz.basha@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>