UPSTREAM: PCI: rockchip: Mark PM functions as __maybe_unused

UPSTREAM: 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.

Change-Id: Ic5f9f9d576049b77fd091488c785d09c46cb9b78
Fixes: 013dd3d5e183 ("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>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
(cherry picked from git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git
commit 0b351c986a5ffedb502632c1b27690c9730d79c4)