radv: emit the guardband state separately from the scissor state

radv: emit the guardband state separately from the scissor state

Only re-emit the scissor state if viewports or scissors change, and
only re-emit the guardband state if viewports, line width or the
current rasterized primitive change.

This should reduce the number of emitted packets when only the line
width or the rasterized primitive change.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18247>