r293331 mistakingly failed to add an assignment of paddr to the rxbuf

but only in the NETMAP code.  This lead to the NETMAP code paths
passing nothing up to userland.

Submitted by:	Ad Schellevis <ad@opnsense.org>
Reported by:	Franco Fichtner <franco@opnsense.org>
MFC after:	1 day

sys/dev/e1000/if_em.c

@@ -4392,6 +4392,7 @@ em_setup_receive_ring(struct rx_ring *rxr)
 
 			addr = PNMB(na, slot + si, &paddr);
 			netmap_load_map(na, rxr->rxtag, rxbuf->map, addr);
+			rxbuf->paddr = paddr;
 			em_setup_rxdesc(&rxr->rx_base[j], rxbuf);
 			continue;
 		}