ethtool: move firmware flashing flag to struct ethtool_netdev_state

Commit 31e0aa99 ("ethtool: Veto some operations during firmware flashing process")
 added a flag module_fw_flash_in_progress to struct net_device.  As
 this is ethtool related state, move it to the recently created
 struct ethtool_netdev_state, accessed via the 'ethtool' member of
 struct net_device.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20240703121849.652893-1-edward.cree@amd.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>