radeon/r300: no need to flush the cmdbuf when changing scissors state in KMM mode

src/mesa/drivers/dri/r300/r300_state.c

@@ -1741,7 +1741,8 @@ static void r300Enable(GLcontext * ctx, GLenum cap, GLboolean state)
 		r300SetPolygonOffsetState(ctx, state);
 		break;
 	case GL_SCISSOR_TEST:
-		radeon_firevertices(&rmesa->radeon);
+		if (!rmesa->radeon.radeonScreen->kernel_mm)
+			radeon_firevertices(&rmesa->radeon);
 		rmesa->radeon.state.scissor.enabled = state;
 		radeonUpdateScissor( ctx );
 		break;

src/mesa/drivers/dri/radeon/radeon_common.c

@@ -257,7 +257,9 @@ void radeonScissor(GLcontext* ctx, GLint x, GLint y, GLsizei w, GLsizei h)
 	radeonContextPtr radeon = RADEON_CONTEXT(ctx);
 	if (ctx->Scissor.Enabled) {
 		/* We don't pipeline cliprect changes */
-		radeon_firevertices(radeon);
+		if (!radeon->radeonScreen->kernel_mm) {
+			radeon_firevertices(radeon);
+		}
 		radeonUpdateScissor(ctx);
 	}
 }