ifnet: Remove if_getamcount()

All uses of this function were incorrect.  if_amcount is a reference
count which tracks the number of times the network stack internally set
IFF_ALLMULTI.  (if_pcount is the corresponding counter for IFF_PROMISC.)

Remove if_getamcount() and fix up callers to get the number of assigned
multicast addresses instead, since that's what they actually want.

Sponsored by:	Klara, Inc.
Reviewed by:	zlei, glebius
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D46523

(cherry picked from commit 408c909)
(cherry picked from commit b513c31)

sys/dev/bxe/bxe.c

@@ -12197,7 +12197,7 @@ bxe_set_rx_mode(struct bxe_softc *sc)
     if (if_getflags(ifp) & IFF_PROMISC) {
         rx_mode = BXE_RX_MODE_PROMISC;
     } else if ((if_getflags(ifp) & IFF_ALLMULTI) ||
-               ((if_getamcount(ifp) > BXE_MAX_MULTICAST) &&
+               (if_llmaddr_count(ifp) > BXE_MAX_MULTICAST &&
                 CHIP_IS_E1(sc))) {
         rx_mode = BXE_RX_MODE_ALLMULTI;
     } else {

sys/dev/liquidio/lio_ioctl.c

@@ -481,7 +481,7 @@ lio_get_new_flags(struct ifnet *ifp)
 		 * Accept all multicast addresses if there are more than we
 		 * can handle
 		 */
-		if (if_getamcount(ifp) > LIO_MAX_MULTICAST_ADDR)
+		if (if_llmaddr_count(ifp) > LIO_MAX_MULTICAST_ADDR)
 			f |= LIO_IFFLAG_ALLMULTI;
 	}
 	if (if_getflags(ifp) & IFF_BROADCAST)

sys/net/if.c

@@ -4387,12 +4387,6 @@ if_getifaddr(if_t ifp)
 	return ((struct ifnet *)ifp)->if_addr;
 }
 
-int
-if_getamcount(if_t ifp)
-{
-	return ((struct ifnet *)ifp)->if_amcount;
-}
-
 int
 if_setsendqready(if_t ifp)
 {

sys/net/if_var.h

@@ -761,7 +761,6 @@ u_int if_foreach_llmaddr(if_t, iflladdr_cb_t, void *);
 u_int if_lladdr_count(if_t);
 u_int if_llmaddr_count(if_t);
 
-int if_getamcount(if_t ifp);
 struct ifaddr * if_getifaddr(if_t ifp);
 
 /* Functions */