sim: clean up some more device detritus

Clean up some more remains of WITH_DEVICES that escaped notice.

We also clean up GETTWI/SETTWI defines in a few ports where they
were copied & pasted and are unused as they happen to be near the
device code.

sim/common/sim-basics.h

@@ -60,7 +60,6 @@ extern int asprintf (char **result, const char *format, ...);
 
 /* Global types that code manipulates */
 
-typedef struct _device device;
 struct hw;
 struct _sim_fpu;