radv: properly align the fence and EOP bug VA on GFX9

If alignement is 0, offets returned by
radv_cmd_buffer_upload_alloc() are always 0. These two
virtual addresses were pointing at the same location.

Cc: 18.3 19.0 <mesa-stable@lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit c2a14869)
[Emil: resolve trivial conflicts]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

Conflicts:
	src/amd/vulkan/radv_cmd_buffer.c