cleanup: Use non-const pointers for non constant cases

We had various cases in which we were using const pointers for
non constant data, and in fact we were allocating and free'ing
them.

So let's handle all these case properly, so that we won't have
newer GLib complaining at us!

libfprint/fpi-ssm.c

@@ -73,7 +73,7 @@
 struct _FpiSsm
 {
   FpDevice               *dev;
-  const char             *name;
+  char                   *name;
   FpiSsm                 *parentsm;
   gpointer                ssm_data;
   GDestroyNotify          ssm_data_destroy;