asahi: Lower 1D to 2D

asahi: Lower 1D to 2D

Khronos APIs require that we support mipmapping even for 1D textures. However,
it isn't clear if this is supported in the hardware, and how it would work even
if it is. But 1D textures are pretty useless, so we just lower 1D textures to 2D
textures instead of worrying about that.

Fixes piles of Piglits relating to 1D textures.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22353>