bnxt_en: Add support for fw managed link down feature.

In the current code, the driver will not shutdown the link during
IFDOWN if there are still VFs sharing the port.  Newer firmware will
manage the link down decision when the port is shared by VFs, so
we can just call firmware to shutdown the port unconditionally and
let firmware make the final decision.

Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -9495,7 +9495,8 @@ static int bnxt_hwrm_shutdown_link(struct bnxt *bp)
 	if (!BNXT_SINGLE_PF(bp))
 		return 0;
 
-	if (pci_num_vf(bp->pdev))
+	if (pci_num_vf(bp->pdev) &&
+	    !(bp->phy_flags & BNXT_PHY_FL_FW_MANAGED_LKDN))
 		return 0;
 
 	bnxt_hwrm_cmd_hdr_init(bp, &req, HWRM_PORT_PHY_CFG, -1, -1);

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -2014,6 +2014,7 @@ struct bnxt {
 #define BNXT_PHY_FL_SHARED_PORT_CFG	PORT_PHY_QCAPS_RESP_FLAGS_SHARED_PHY_CFG_SUPPORTED
 #define BNXT_PHY_FL_PORT_STATS_NO_RESET	PORT_PHY_QCAPS_RESP_FLAGS_CUMULATIVE_COUNTERS_ON_RESET
 #define BNXT_PHY_FL_NO_PHY_LPBK		PORT_PHY_QCAPS_RESP_FLAGS_LOCAL_LPBK_NOT_SUPPORTED
+#define BNXT_PHY_FL_FW_MANAGED_LKDN	PORT_PHY_QCAPS_RESP_FLAGS_FW_MANAGED_LINK_DOWN
 
 	u8			num_tests;
 	struct bnxt_test_info	*test_info;