i965: Compile the fp64 program based on nir options

i965: Compile the fp64 program based on nir options

Instead of looking the devinfo directly, look at the lowering options we
provided to NIR.  This is more accurate as it's now checking for "do we
need full software lowering" rather than a hardware bit.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>