bnx2x: Don't log mc removal needlessly

When mc configuration changes bnx2x_config_mcast() can return 0 for
success, negative for failure and positive for benign reason preventing
its immediate work, e.g., when the command awaits the completion of
a previously sent command.

When removing all configured macs on a 578xx adapter, if a positive
value would be returned driver would errneously log it as an error.

Fixes: c7b7b483 ("bnx2x: Don't flush multicast MACs")
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

@@ -12729,7 +12729,7 @@ static int bnx2x_set_mc_list(struct bnx2x *bp)
 	} else {
 		/* If no mc addresses are required, flush the configuration */
 		rc = bnx2x_config_mcast(bp, &rparam, BNX2X_MCAST_CMD_DEL);
-		if (rc)
+		if (rc < 0)
 			BNX2X_ERR("Failed to clear multicast configuration %d\n",
 				  rc);
 	}