r600g: avoid useless shader rebuild at draw call

Avoid rebuilding constant shader state at each draw call,
factor out spi update that might change at each draw call.
Best would be to update spi only when revealent states
change (likely only flat shading & sprite point).

Signed-off-by: Jerome Glisse <jglisse@redhat.com>

src/gallium/drivers/r600/r600_shader.h

@@ -38,7 +38,6 @@ struct r600_shader_io {
 struct r600_shader {
 	unsigned		processor_type;
 	struct r600_bc		bc;
-	boolean			flat_shade;
 	unsigned		ninput;
 	unsigned		noutput;
 	unsigned		nlds;