etnaviv: Emit vertex buffers consecutively

etnaviv: Emit vertex buffers consecutively

Vertex buffer legacy state is no longer picked up with new drawing
commands. Change to use different cases depending on the number of
vertex streams in the GPU specs.

This results in slightly more compact state emission as well, on all
vivantes.

Signed-off-by: Wladimir J. van der Laan <laanwj@gmail.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>