Previously we used "flags" for both:

  - the bitmask of features we support (segments, ASPM, MSI, etc.), and
  - the bitmask of features we want to control (native hotplug, AER, etc.)

To reduce confusion, this patch splits this into two variables:
"support" is the bitmask of features we support, and "control" is the
bitmask of features we want to control.  No functional change.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>