i965: Use BRW_NEW_CONTEXT for gen7_disable rather than BRW_NEW_BATCH.

These don't need to be re-disabled on every batch if we're using
hardware contexts.  (If we're not, this is equivalent.)

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/drivers/dri/i965/gen7_disable.c

@@ -127,7 +127,7 @@ disable_stages(struct brw_context *brw)
 const struct brw_tracked_state gen7_disable_stages = {
    .dirty = {
       .mesa  = 0,
-      .brw   = BRW_NEW_BATCH,
+      .brw   = BRW_NEW_CONTEXT,
       .cache = 0,
    },
    .emit = disable_stages,