i40e/i40evf: Refactor PHY structure and add phy_capabilities enum

Remove unused members in the PHY structure and add a new member to store
all the capabilities the PHY has as reported by the FW. This information
will help us determine what speeds the device is capable of when link is
down.

Also add an enum to decode the PHY types the NVM is capable of.
Use the phy_types variable to determine what phy types are possible
when link is down instead of device id as it will be more accurate.

When on a backplane device, we do not support changing any settings,
however we should display all the phy_types we are capable of so if we
see a backplane dev ID set supported and advertised purely based on
the phy_types variable.

Change-ID: Ia75d560f1fcd30c54cbfb7458690c5867559a930
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>