radv: add a write-combining host-local memory type

radv: add a write-combining host-local memory type

Add the new memory type between the two device-local types. This makes
the list of supported memory types look like this:

1) DEVICE_LOCAL |              |               |
2)              | HOST_VISIBLE | HOST_COHERENT |
3) DEVICE_LOCAL | HOST_VISIBLE | HOST_COHERENT |
4)              | HOST_VISIBLE | HOST_COHERENT | HOST_CACHED

With this order a client that searches for a HOST_VISIBLE and
HOST_COHERENT memory type using the algorithm described in section
10.2 of the Vulkan specification (revision 32) will find the host-
local memory type first.

A client that requires the memory type to be HOST_VISIBLE and
HOST_COHERENT, but not DEVICE_LOCAL is most likely searching for
a memory type suitable for staging buffers / images.
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>