iris: Fix iris_flush_and_dirty_history to actually dirty history.

When I split iris_flush_and_dirty_history into two helper functions,
I accidentally made it stop dirtying.  Which was...sort of the point.

Fixes: 21688a30 iris: Split iris_flush_and_dirty_for_history into two helpers.
(cherry picked from commit 64fb20ed)
[Juan A. Suarez: resoved trivial conflicts]
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>

Conflicts:
	src/gallium/drivers/iris/iris_resource.c