sim: cris: add error fallbacks when decoding condition & swap codes

The condition & swap code decoder only checks known bits and sets
based on that.  If the variable is out of range, it ends up returning
uninitialized data.  Turn that case into a hard error.

This fixes build warnings like:
sim/cris/semcrisv10f-switch.c:13115:11: error:
	variable 'tmp_condres' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
3 files changed