panfrost: Upload vertex descriptors to *transient* memory

panfrost: Upload vertex descriptors to *transient* memory

It's not legal to reuse the vertex shader descriptor across frames now
that we patch it at draw-time, so upload to transient memory.

Ideally, we could be smarter about this such that subsequent draws with
the same vertex shader and same patched state would reuse the
descriptor, but for now, let's simply achieve correctness.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>