Add new ->probe_reset operation to ata_port_operations obsoleting
->phy_reset.  The main difference from ->phy_reset is that the new
operation is not allowed to manipulate libata internals directly.
It's not allowed to configure or disable the port or devices.  It can
only succeed or fail and classify attached devices into passed
@classes.

This change gives more control to higher level and eases sharing reset
methods with EH.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>