[PATCH] libata: fix comment regarding setting cable type

The comment above ata_std_postreset() specified that setting cable
type is the responsibility of postreset(), which isn't possible /
optimal depending on controller / driver.  This patch kills the
comment.  Setting cable type is responsibility of ->probe_reset.
libata doesn't care whether it's done in probeinit, reset or
postreset.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>