AHCI: Increase link timeout to 200ms

In 73545f75 "ahci: wait longer for link" I increased the
timeout to 40ms based on the observed behaviour of a WD disk on a
Cubietruck. Since then Karsten Merker and myself have both
observed timeouts with HGST disks (Karsten on Cubietruck, me on
Cubieboard2). Increasing the timeout to ~175ms fixes this, so go
to 200ms for a bit of headroom.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Karsten Merker <merker@debian.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>