ahci: add workaround for on-board 5723s on some gigabyte boards

Some gigabytes have on-board SIMG5723s connected to JMB ahcis.  These
are used to implement hardware raid.  Unfortunately some firmware
revisions on these 5723s don't bring the link down when all the
downstream ports are unoccupied while not responding to reset protocol
which makes libata think that there's device attached to the port but
is not responding and retry.  This results in painfully wrong boot
detection time for these ports when they're empty.

This patch quirks those boards such that ahci gives up after the
initial timeout.  Combined with parallel probing, this gives quick
enough probing and also is safe because SIMG5723 will respond to the
first try if any of the downstream ports is occupied.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Marc Bowes <marcbowes@gmail.com>
Reported-by: Nicolas Mailhot <Nicolas.Mailhot@LaPoste.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>