Instead of using the driver-specific rtsx_pci_update_cfg_byte() to update
the PCIe Link Control Register, use pcie_capability_clear_and_set_word()
like the rest of the kernel does.  This makes it easier to maintain ASPM
across the PCI core and drivers.

Remove the now-unused rtsx_pci_update_cfg_byte() and ASPM_MASK_NEG
definitions.

No functional change intended.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20200521180545.1159896-5-helgaas@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>