[PATCH] libata: kill SError clearing in sata_std_hardreset().

Don't clear SError in sata_std_hardreset().  This makes hardreset act
identically to ->phy_reset register-wise.

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