freedreno/ir3: Use RESINFO for a6xx image size queries.

freedreno/ir3: Use RESINFO for a6xx image size queries.

The closed GL driver uses resinfo on images with the writeonly flag (using
the texture-path's getsize only for readonly images).  The closed vulkan
driver seems to use resinfo regardless.  Using resinfo doesn't need any
fixups after the instruction.  It also avoids one of the needs for the
TEX_CONST state for the image, which is awkward to set up in the GL
driver.

The new handler goes into ir3_a6xx to be next to the other current image
code, but the a4xx version is left in place because it wants a bunch of
sampler helpers.

Fixes assertion failure in dEQP-VK.image.image_size.buffer.readonly_32.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3501>