scsi: hisi_sas: Don't create debugfs dump folder twice

Due to a merge error, we attempt to create 2x debugfs dump folders, which
fails:
[  861.101914] debugfs: Directory 'dump' with parent '0000:74:02.0'
already present!

This breaks the dump function.

To fix, remove the superfluous attempt to create the folder.

Fixes: 7ec7082c ("scsi: hisi_sas: Add hisi_sas_debugfs_alloc() to centralise allocation")
Link: https://lore.kernel.org/r/1571926105-74636-2-git-send-email-john.garry@huawei.com


Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>