i40e: Fix overwriting flow control settings during driver loading

During driver loading flow control settings were written to FW
using a variable which was always zero, since it was being set
only by ethtool. This behavior has been corrected and driver
no longer overwrites the default FW/NVM settings.

Fixes: 373149fc ("i40e: Decrease the scope of rtnl lock")
Signed-off-by: Dawid Lukwinski <dawid.lukwinski@intel.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>