etnaviv: update HW headers and fix provoking vertex

etnaviv: update HW headers and fix provoking vertex

Now that the real meaning of the 2 bits in PA_SYSTEM_MODE is known,
we can set them according to the rasterizer state, which fixes uses
that are setting provoking vertex first.

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