qdev: Avoid using prop->name unnecessarily

qdev: Avoid using prop->name unnecessarily

We already get the property name as argument to the property
getter and setters, we don't need to use prop->name.  This will
make it easier to remove the Property.name field in the future.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20201211220529.2290218-20-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>