i40e: link_down_on_close private flag support

This patch introduces new ethtool private flag used for
forcing true link state. Function i40e_force_link_state that implements
this functionality was added, it sets phy_type = 0 in order to
work-around firmware's LESM. False positive error messages were
suppressed.

The ndo_open() should not succeed if there were issues with forcing link
state to be UP.

Added I40E_PHY_TYPES_BITMASK define with all phy types OR-ed together in
one bitmask.  Added after phy type definition, so it will be hard to
forget to include new phy types to the bitmask.

Signed-off-by: Mariusz Stachura <mariusz.stachura@intel.com>
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>