i40e: redfine I40E_PHY_TYPE_MAX

Since I40E_PHY_TYPE_MAX is used as an iterator, usually combined with
some sort of bit-shifting, it should only include actual PHY types and
not error cases. Move it up in the enum declaration so that loops only
iterate across valid PHY types.

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>