Split the hardware type enum and the hw feature flags bits into separate
fields in the softc; they're ORed together in the ofw_compat_data.

I already caught myself doing 'sc->fectype == <enum val>' without masking
out the feature bits in one place, and that's sure to happen again.
Glomming them together is convenient for storing them in the ofw_compat_data
array, but there's no reason to keep them together in the softc.