pci: clear osc support flags if no _OSC method

pci: clear osc support flags if no _OSC method

So it looks like pci aer code will call pci_osc_support_set to tell the
firmware about  OSC_EXT_PCI_CONFIG_SUPPORT flag.  that causes
ctrlset_buf[OSC_SUPPORT_TYPE] to evaluate to true when pciehp calls
pci_osc_control_set() is called (to attempt to use OSC to gain native
pcie control from firmware), regardless of whether or not _OSC was
actually successfully executed.  That causes this section of code:
 if (ctrlset_buf[OSC_SUPPORT_TYPE] &&
                ((global_ctrlsets & ctrlset) != ctrlset)) {
                return AE_SUPPORT;
        }
to be hit.

This patch will reset the OSC_SUPPORT_TYPE field if _OSC fails, and then
would allow pciehp to go ahead and try to run _OSC again.

Signed-off-by:  Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>