agx: Check that we don't push too much

agx: Check that we don't push too much

Currently we don't have a good mechanism for this other than being
careful... assert() at least. The long term plan is to lift the
UBO/VBO lowerings into NIR, making the sysval requirements visible in
the NIR. (And possibly moving to a descriptor set model to better match
Vulkan? I need to talk to jekstrand about what we want to do here long
term.)

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18813>