sim: update device_error() prototype

sim: update device_error() prototype

The device_error() takes a printf style string, so update the prototype
accordingly.  The message should be const and it should use an attribute.
This fixes gcc warnings like:

sim-core.c: In function 'sim_core_map_attach':
sim-core.c:200: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type
sim-core.c:237: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type
sim-core.c: In function 'sim_core_attach':
sim-core.c:304: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type
sim-core.c:314: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type
sim-core.c:335: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type
sim-core.c:348: warning: passing argument 2 of 'device_error' discards qualifiers from pointer target type