Avoton AHCI occasionally sees drive probe timeouts at driver load time.
When this happens SCR_STATUS indicates device detected, but no D2H FIS
reception.  Reset the internal link state machines by bouncing
port-enable in the PCS register when this occurs.

Cc: <stable@vger.kernel.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NTejun Heo <tj@kernel.org>