iris: Add missed tile flush flag

Without adding PIPE_CONTROL_TILE_CACHE_FLUSH into iris_emit_pipe_control gen12+ (UHD 750 in my case) has issues with textures.

Related-to: #5029 (closed) Fixes: c85ea824 ('iris: reduce redundant tile cache flushes')

Signed-off-by: Mykhailo Skorokhodov mykhailo.skorokhodov@globallogic.com Reviewed-by: Felix DeGrood felix.j.degrood@intel.com