i40e: avoid redundant VF link state updates

i40e: avoid redundant VF link state updates

Multiple sources can request VF link state changes with identical
parameters. For example, OpenStack Neutron may request to set the VF link
state to IFLA_VF_LINK_STATE_AUTO during every initialization or user can
issue: `ip link set <ifname> vf 0 state auto` multiple times. Currently,
the i40e driver processes each of these requests, even if the requested
state is the same as the current one. This leads to unnecessary VF resets
and can cause performance degradation or instability in the VF driver,
particularly in environment using Data Plane Development Kit (DPDK).

With this patch i40e will skip VF link state change requests when the
desired link state matches the current configuration. This prevents
unnecessary VF resets and reduces PF-VF communication overhead.

To reproduce the problem run following command multiple times
on the same interface: 'ip link set <ifname> vf 0 state auto'
Every time command is executed, PF driver will trigger VF reset.

Co-developed-by: Robert Malz <robert.malz@canonical.com>
Signed-off-by: Robert Malz <robert.malz@canonical.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>