lavapipe: fix vertex attributes/descriptor binding
Yo' dawg, I heard you like bindings in your bindings.
When you have VertexAttribs with a binding, it's not an index into the VertexBindings, you have to match it to the VertexBinding with the same binding value.
This fixes dEQP-VK.pipeline.extended_dynamic_state.after_pipelines.vertex_input_multiple_bindings and some others.
Fixes: 5951d2ab ("lavapipe: implement EXT_vertex_input_dynamic_state")