In case INET is not defined, then ANCACHE is not defined and

the sc does not have 'an_have_rssimap' variable.
Add an ANCACHE check to poperly hide the case and make an(4)
compile without INET.

MFC after:	2 months

sys/dev/an/if_an.c

@@ -2686,8 +2686,10 @@ an_init(void *xsc)
 		}
 	}
 
+#ifdef ANCACHE
 	if (sc->an_have_rssimap)
 		sc->an_config.an_rxmode |= AN_RXMODE_NORMALIZED_RSSI;
+#endif
 
 	/* Set the ssid list */
 	sc->an_ssidlist.an_type = AN_RID_SSIDLIST;