PCI ACPI: Added a function to register _OSC with only PCIe devices.

The function pci_osc_support_set() traverses every root bridge when
checking for _OSC support for a capability.  It quits as soon as it finds a
device/bridge that doesn't support the requested capability. This won't
work for systems that have mixed PCI and PCIe bridges when checking for
PCIe features.  I split this function into two -- pci_osc_support_set() and
pcie_osc_support_set(). The latter is used when only PCIe devices should be
traversed.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>