NFSD: use correct reservation type in nfsd4_scsi_fence_client

The reservation type argument for the pr_preempt call should match the
one used in nfsd4_block_get_device_info_scsi.

Fixes: f99d4fbdae67 ("nfsd: add SCSI layout support")
Cc: [e-mail]
Signed-off-by: Dai Ngo <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

fs/nfsd/blocklayout.c

···
 	struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;
 
 	bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
-			nfsd4_scsi_pr_key(clp), 0, true);
+			nfsd4_scsi_pr_key(clp),
+			PR_EXCLUSIVE_ACCESS_REG_ONLY, true);
 }
 
 const struct nfsd4_layout_ops scsi_layout_ops = {