scsi: libsas: remove the exporting of sas_wait_eh

The function sas_wait_eh is declared static and marked EXPORT_SYMBOL, which
is at best an odd combination. Because the function is not used outside of
the drivers/scsi/libsas/sas_scsi_host.c file it is defined in, this commit
removes the EXPORT_SYMBOL() marking.

Signed-off-by: Denis Efremov <efremov@linux.com>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>