Fix nfs4.2 return -EINVAL when do dedupe operation

dedupe_file_range operations is combiled into remap_file_range.
But in nfs42_remap_file_range, it's skiped for dedupe operations.
Before this patch:
  # dd if=/dev/zero of=nfs/file bs=1M count=1
  # xfs_io -c "dedupe nfs/file 4k 64k 4k" nfs/file
  XFS_IOC_FILE_EXTENT_SAME: Invalid argument
After this patch:
  # dd if=/dev/zero of=nfs/file bs=1M count=1
  # xfs_io -c "dedupe nfs/file 4k 64k 4k" nfs/file
  deduped 4096/4096 bytes at offset 65536
  4 KiB, 1 ops; 0.0046 sec (865.988 KiB/sec and 216.4971 ops/sec)
Signed-off-by: Xiaoli Feng <fengxiaoli0714@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4file.c

@@ -187,7 +187,7 @@ static loff_t nfs42_remap_file_range(struct file *src_file, loff_t src_off,
 	bool same_inode = false;
 	int ret;
 
-	if (remap_flags & ~REMAP_FILE_ADVISORY)
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
 	/* check alignment w.r.t. clone_blksize */