mesa: fix error checking for getting zero-sized texture images

mesa: fix error checking for getting zero-sized texture images

Commit 17f714836 (mesa: rearrange texture error checking order) moved
the width/height/depth == 0 allowance before checking if the image was
there. This was in part due to depth having to be == 1 for 2D images and
width having to be == 1 for 1D images. Instead relax the height/depth
checks to also accept 0 as valid.

With this change,

  bin/arb_direct_state_access-get-textures

starts passing again.

Fixes: 17f714836 (mesa: rearrange texture error checking order)
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Brian Paul <brianp@vmware.com>