PCI: apple: Enable clock gating

These pokes are not required to make the PCIe port work, but it sounds
like this should save some power at least.

Link: https://lore.kernel.org/r/20211117141916.197192-1-marcan@marcan.st
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>

Author: marcan

drivers/pci/controller/pcie-apple.c

@@ -553,6 +553,9 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
 		return ret;
 	}
 
+	rmw_clear(PORT_REFCLK_CGDIS, port->base + PORT_REFCLK);
+	rmw_clear(PORT_APPCLK_CGDIS, port->base + PORT_APPCLK);
+
 	ret = apple_pcie_port_setup_irq(port);
 	if (ret)
 		return ret;