The comment claims we will call host->ops->map() to update the flags if
we find a previously established mapping, but we never did.  We used
to call remap, but that call was removed in da051980 (powerpc: Remove
irq_host_ops->remap hook).
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>