qom: Clean up inconsistent use of gchar * vs. char *

Uses of gchar * in qom/object.h:

* ObjectProperty member @name

  Functions that take a property name argument all use char *.  Change
  the member to match.

* ObjectProperty member @type

  Functions that take a property type argument or return it all use
  char *.  Change the member to match.

* ObjectProperty member @description

  Functions that take a property description argument all use char *.
  Change the member to match.

* object_resolve_path_component() parameter @part

  Path components are property names.  Most callers pass char *
  arguments.  Change the parameter to match.  Adjust the few callers
  that pass gchar * to pass char *.

* Return value of object_get_canonical_path_component(),
  object_get_canonical_path()

  Most callers convert their return values right back to char *.
  Change the return value to match.  Adjust the few callers where that
  would add a conversion to gchar * to use char * instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-3-armbru@redhat.com>

hw/ppc/spapr_drc.c

@@ -518,7 +518,7 @@ static void realize(DeviceState *d, Error **errp)
     SpaprDrc *drc = SPAPR_DR_CONNECTOR(d);
     Object *root_container;
     gchar *link_name;
-    gchar *child_name;
+    char *child_name;
     Error *err = NULL;
 
     trace_spapr_drc_realize(spapr_drc_index(drc));