Revert: "vfio-pci: Mask INTx if a device is not capabable of enabling it"

Revert: "vfio-pci: Mask INTx if a device is not capabable of enabling it"

This reverts commit 831f6ae4119dab2c279e2003fb71a7c5346fe615

The intent of commit 831f6ae4119d ("vfio-pci: Mask INTx if a device is
not capabable of enabling it") was to disallow the user from seeing
that the device supports INTx if the platform is incapable of enabling
it.  The detection of this case however incorrectly includes devices
which natively do not support INTx, such as SR-IOV VFs, and further
discussions reveal gaps even for the target use case.

Reported-by: Arjun Vynipadath <arjun@chelsio.com>
Fixes: 831f6ae4119d ("vfio-pci: Mask INTx if a device is not capabable of enabling it")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>