scsi: libsas: aic94xx: hisi_sas: mvsas: pm8001: Use dev_is_expander()

Many times in libsas, and in LLDDs which use libsas, the check for an
expander device is re-implemented or open coded.

Use dev_is_expander() instead. We rename this from
sas_dev_type_is_expander() to not spill so many lines in referencing.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>