liquidio: moved wait_for_pending_requests to octeon_network.h

Moving common function wait_for_pending_requests to octeon_network.h

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>