scsi: libsas: initialize sas_phy status according to response of DISCOVER

scsi: libsas: initialize sas_phy status according to response of DISCOVER

The status of SAS PHY is in sas_phy->enabled. There is an issue that the
status of a remote SAS PHY may be initialized incorrectly: if disable
remote SAS PHY through sysfs interface (such as echo 0 >
/sys/class/sas_phy/phy-1:0:0/enable), then reboot the system, and we
will find the status of remote SAS PHY which is disabled before is
1 (cat /sys/class/sas_phy/phy-1:0:0/enable). But actually the status of
remote SAS PHY is disabled and the device attached is not found.

In SAS protocol, NEGOTIATED LOGICAL LINK RATE field of DISCOVER response
is 0x1 when remote SAS PHY is disabled. So initialize sas_phy->enabled
according to the value of NEGOTIATED LOGICAL LINK RATE field.

Signed-off-by: chenxiang <chenxiang66@hisilicon.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>