sim: ppc: clean up various warnings

A random grab bag of minor fixes to enable -Werror for this port.

Cast address vars to long when the format was using %l.
Use %zu with sizeof operations.
Add const to a bunch of strings.
Trim unused variables.
Fix sizeof call to calculate target storage and not the pointer itself.

sim/ppc/device.c

@@ -180,10 +180,9 @@ device_full_name(device *leaf,
                  unsigned sizeof_buf)
 {
   /* get a buffer */
-  char full_name[1024];
-  if (buf == (char*)0) {
-    buf = full_name;
-    sizeof_buf = sizeof(full_name);
+  if (buf == NULL) {
+    sizeof_buf = 1024;
+    buf = malloc(sizeof_buf);
   }
 
   /* construct a name */
@@ -211,9 +210,6 @@ device_full_name(device *leaf,
     strcat (buf, unit);
   }
   
-  /* return it usefully */
-  if (buf == full_name)
-    buf = (char *) strdup(full_name);
   return buf;
 }
 
@@ -1915,8 +1911,6 @@ INLINE_DEVICE\
 device_clean(device *me,
 	     void *data)
 {
-  psim *system;
-  system = (psim*)data;
   TRACE(trace_device_init, ("device_clean - initializing %s", me->path));
   clean_device_interrupt_edges(&me->interrupt_destinations);
   clean_device_instances(me);