i965: Require softpin support for Cannonlake and later.

i965: Require softpin support for Cannonlake and later.

This isn't strictly necessary, but anyone running Cannonlake will
already have Kernel 4.5 or later, so there's no reason to support
the relocation model on Gen10+.

This will let us avoid dealing with them for new features.

Reviewed-by: Scott D Phillips <scott.d.phillips@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>