PCI: rockchip: Mark PM functions as __maybe_unused

When CONFIG_PM_SLEEP is disabled, we get harmless build warnings:

  host/pcie-rockchip.c:1267:12: error: 'rockchip_pcie_resume_noirq' defined but not used [-Werror=unused-function]
  host/pcie-rockchip.c:1240:12: error: 'rockchip_pcie_suspend_noirq' defined but not used [-Werror=unused-function]

Marking both functions as __maybe_unused avoids the warning without the
need for #ifdef around them.

Fixes: 013dd3d5 ("PCI: rockchip: Add system PM support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>

drivers/pci/host/pcie-rockchip.c

@@ -1217,7 +1217,7 @@ static int rockchip_pcie_wait_l2(struct rockchip_pcie *rockchip)
 	return 0;
 }
 
-static int rockchip_pcie_suspend_noirq(struct device *dev)
+static int __maybe_unused rockchip_pcie_suspend_noirq(struct device *dev)
 {
 	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
 	int ret;
@@ -1244,7 +1244,7 @@ static int rockchip_pcie_suspend_noirq(struct device *dev)
 	return ret;
 }
 
-static int rockchip_pcie_resume_noirq(struct device *dev)
+static int __maybe_unused rockchip_pcie_resume_noirq(struct device *dev)
 {
 	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
 	int err;