anv,radv: Disable VK_EXT_pci_bus_info

anv,radv: Disable VK_EXT_pci_bus_info

The Vulkan working group recently discovered that we made a mistake in
assuming that PCI domains are 16-bit even though they can potentially be
32-bit values.  To fix this, the next spec update will change the types
in the VK_EXT_pci_bus_info struct to be 32 bits which will be a
backwards-incompatible change.  Normally, Khronos tries very hard to
never make backwards incompatible changes to specs.  Hopefully, the
extension is new enough (2 months) that there are no shipping apps which
use the extension so this should be safe.

This commit disables the extension for both anv and radv in mesa and
should be back-ported to 18.3 ASAP so we avoid any potential issues with
new apps running on old drivers.  I'll send out a commit (which we can
also back-port to 18.3 if we really care) to re-enable the extension in
both drivers once this week's spec update ships.  The one known use of
this extension is internal to mesa and will continue working with the
extension disabled and will naturally update when we get a new header.

Cc: "18.3" <mesa-stable@lists.freedesktop.org>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>