qdev: Wrap getters and setters in separate helpers

qdev: Wrap getters and setters in separate helpers

We'll add extra code to the qdev property getters and setters, so
add wrapper functions where additional actions can be performed.

The new functions have a "field_prop_" prefix instead of "qdev_"
because the code will eventually be moved outside
qdev-properties.c, to common QOM code.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20201211220529.2290218-23-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>