radv: Don't expose heaps with 0 memory.

It confuses CTS. This pregenerates the heap info into the
physical device, so we can use it for translating contiguous
indices into our "standard" ones.

This also makes the WSI a bit smarter in case the first preferred
heap does not exist.

Reviewed-by: Dave Airlie <airlied@redhat.com>
CC: <mesa-stable@lists.freedesktop.org>
(cherry picked from commit 80672142)
[Andres Gomez: resolve trivial conflicts]
Signed-off-by: Andres Gomez <agomez@igalia.com>

Conflicts:
	src/amd/vulkan/radv_device.c
	src/amd/vulkan/radv_private.h
	src/amd/vulkan/radv_wsi.c