nfsd4: fix double free in nfsd4_do_async_copy()

This frees "copy->nf_src" before and again after the goto.

Fixes: ce0887ac ("NFSD add nfs4 inter ssc to nfsd4_copy")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -1469,7 +1469,6 @@ static int nfsd4_do_async_copy(void *data)
 		copy->nf_src->nf_file = nfs42_ssc_open(copy->ss_mnt, &copy->c_fh,
 					      &copy->stateid);
 		if (IS_ERR(copy->nf_src->nf_file)) {
-			kfree(copy->nf_src);
 			copy->nfserr = nfserr_offload_denied;
 			nfsd4_interssc_disconnect(copy->ss_mnt);
 			goto do_callback;