Pull up following revision(s) (requested by msaitoh in ticket #690):
sys/dev/pci/ixgbe/ixgbe_82599.c: revision 1.17
sys/dev/pci/ixgbe/ixgbe.c: revision 1.138
sys/dev/pci/ixgbe/ixv.c: revision 1.90
sys/dev/pci/ixgbe/ixgbe.c: revision 1.139
sys/dev/pci/ixgbe/ixgbe_common.c: revision 1.19
sys/dev/pci/ixgbe/ixgbe_common.h: revision 1.11
sys/dev/pci/ixgbe/ixgbe.h: revision 1.38
sys/dev/pci/ixgbe/ixgbe_api.h: revision 1.12
sys/dev/pci/ixgbe/ixgbe.h: revision 1.39
sys/dev/pci/ixgbe/ixgbe_x550.c: revision 1.10
sys/dev/pci/ixgbe/ixgbe_x550.c: revision 1.11
sys/dev/pci/ixgbe/ix_txrx.c: revision 1.37
sys/dev/pci/ixgbe/ix_txrx.c: revision 1.38
sys/dev/pci/ixgbe/ixgbe.c: revision 1.140
sys/dev/pci/ixgbe/ixgbe_common.c: revision 1.20
sys/dev/pci/ixgbe/ixgbe.c: revision 1.141
sys/dev/pci/ixgbe/ixgbe.c: revision 1.142
sys/dev/pci/ixgbe/ixgbe.c: revision 1.143
sys/dev/pci/ixgbe/ixgbe.h: revision 1.40
sys/dev/pci/ixgbe/ixgbe_x550.h: revision 1.4

Fix the problem between eitr and link_speed.

In ixgbe_msix_que(), que->eitr_setting is limited to IXGBE_MIN_RSC_EITR_10G1G
when link_speed is 1Gbps or 10Gbps. However, que->eitr_setting is set to EITR
register in the *next* Tx/Rx interrupt. If link_speed changes from 100Mbps to
1Gbps ro 10Gbps, que->eitr_setting which is not limited can be set to EITR
register, that is, the problem fixed by ixgbe.c:r1.124 can occur in this case.

To fix this case, que->eitr_setting should be clear when link_speed is changed
or link state is changed.

Furthermore, expand the variants used for AIM (txr->bytes, txr->packets,
rxr->bytes and rxr->packets) from u32 to u64 to avoid wraparound which causes
que->eitr_setting calculation mistake.
XXX pullup-8

Don't write EIMC directly. It is required to manage with struct ix_queue status.
XXX pullup-8

-  Add missing IFM_NONE support. If a interface support linkdown,
  "ifconfig ixgN media none" drpos link.  Not all interface can do link down.
Tested:
        82598 AT2 (T)
        92599 SF+(SFI) (X520-DA2)
        X540
        X550-T1
        X550EM_x (X10SDV-8C-TLN4F)
        X550EM_a (A2SDi-H-TP4F port 0, 1 (T))
Doesn't work:
        X550EM_a (A2SDi-H-TP4F port 2, 3 (SFP+ (KR)))
        X550EM_a (MA10-ST0 port 2, 3 (SFP+ (SFI)))
        (Denverton SFP+ can't force link down because SFP+'s TX_DISABLE pin is
        pull down. Is there a way to shutdown SFP+ cage's power?)
Not tested:
        82598 fiber.
- Change some functions static.

Avoid issues caused by sending old packets at next link-up time.

This modification consists by the following two parts.
    - drain packets in if_snd queue or corresponding txr->txr_interq
      when link_active == false in ifp->if_start(), ifp->if_transmit(),
      and deferred Tx processing
    - drain packets in if_snd queue and all of txr->txr_interq's
      at link-down time
ok by msaitoh@n.o.

Fix long standing bug that 82598 SFP+ panics in ixgbe_handle_mod() because
hw->mac.ops.setup_sfp is NULL. This change is a part of FreeBSD r327031.

Fix a bug that "ifconfig ixgN down up" forgot IFM_NONE setting.
- Don't assume autoneg == 0 is the first call of ixgbe_config_link().
  Check ifm_media, too.
- Don't override autoneg_advertised in ixgbe_get_phy_id_fw() to not to
  be inconsistent with if_media value.

(martin)