powerpc/axonram: Fix module autoload for OF platform driver

This platform driver has a OF device ID table but the OF module
alias information is not created so module autoloading won't work.
Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/axonram.c

@@ -313,6 +313,7 @@ static const struct of_device_id axon_ram_device_id[] = {
 	},
 	{}
 };
+MODULE_DEVICE_TABLE(of, axon_ram_device_id);
 
 static struct platform_driver axon_ram_driver = {
 	.probe		= axon_ram_probe,