sim: frv/m32r: back out hard failure when dv-sockser is not available

sim: frv/m32r: back out hard failure when dv-sockser is not available

These sims have optional support for the dv-sockser model, so do not make
them hard failures.  The Makefile made it seem like they didn't actually
support things dynamically, but a further code dive into the source and
the Makefile shows that things work out.