NFSD: remove redundant assignment operation

Commit 5826e09b ("NFSD: OP_CB_RECALL_ANY should recall both read and
write delegations") added a new assignment statement to add
RCA4_TYPE_MASK_WDATA_DLG to ra_bmval bitmask of OP_CB_RECALL_ANY. So the
old one should be removed.

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>