nv20: disable depth writes in hw init

Probably not necessary, but just in case. Depth registers point to the
color buffer, when there is no depth buffer.

Signed-off-by: Pekka Paalanen <pq@iki.fi>

src/gallium/drivers/nv20/nv20_context.c

@@ -263,7 +263,7 @@ static void nv20_init_hwctx(struct nv20_context *nv20)
 	BEGIN_RING(kelvin, NV20TCL_DEPTH_FUNC, 1);
 	OUT_RING  (NV20TCL_DEPTH_FUNC_LESS);
 	BEGIN_RING(kelvin, NV20TCL_DEPTH_WRITE_ENABLE, 1);
-	OUT_RING  (1);
+	OUT_RING  (0);
 	BEGIN_RING(kelvin, NV20TCL_DEPTH_TEST_ENABLE, 1);
 	OUT_RING  (0);
 	BEGIN_RING(kelvin, NV20TCL_POLYGON_OFFSET_FACTOR, 2);