intel: Fix application of PSO-defined scissor state

- Use correct flag
- Use scissor count rather than viewport count

V2: Make it actually work. Serves me right for not testing exactly the
code I sent to the ML.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Tobin Ehlis <tobin@lunarg.com>
4 files changed