agp/ati: Use PCI_COMMAND instead of hard-coded 4
agp/ati: Use PCI_COMMAND instead of hard-coded 4

We're accessing the PCI_COMMAND register here, so use the appropriate
#define.  The bit we're writing (1 << 14) isn't defined by the PCI or PCIe
spec, so we don't have a name for it.

No functional change.

Signed-off-by: Bjorn Helgaas <f10ec01be0c6b54271af5c550cd257810bdf3268@google.com>
KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs