ixgbevf: fix getting link speed data for E610 devices

ixgbevf: fix getting link speed data for E610 devices

E610 adapters no longer use the VFLINKS register to read PF's link
speed and linkup state. As a result VF driver cannot get actual link
state and it incorrectly reports 10G which is the default option.
It leads to a situation where even 1G adapters print 10G as actual
link speed. The same happens when PF driver set speed different than 10G.

Add new mailbox operation to let the VF driver request a PF driver
to provide actual link data. Update the mailbox api to v1.6.

Incorporate both ways of getting link status within the legacy
ixgbe_check_mac_link_vf() function.

Fixes: 4c44b450c69b ("ixgbevf: Add support for Intel(R) E610 device")
Co-developed-by: Andrzej Wilczynski <andrzejx.wilczynski@intel.com>
Signed-off-by: Andrzej Wilczynski <andrzejx.wilczynski@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20251009-jk-iwl-net-2025-10-01-v3-2-ef32a425b92a@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>