nvk: clean up direct u_gralloc dep

The u_gralloc fallback backend exists as a best effort attempt and it
does log in the Android logcat so can be easily identified if not WAI.
So far there's no Vulkan impl in mesa could reasonably work with the
fallback backend alone, so if that becomes a real pain, we can exclude
it from inside vk_android_get_ugralloc runtime helper.

Also drop redundant ANB header.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36386>
2 files changed