NFSD: Remove "inline" directives on op_rsize_bop helpers

These helpers are always invoked indirectly, so the compiler can't
inline these anyway. While we're updating the synopses of these
helpers, defensively convert their parameters to const pointers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/xdr4.h

@@ -889,7 +889,8 @@ struct nfsd4_operation {
 	u32 op_flags;
 	char *op_name;
 	/* Try to get response size before operation */
-	u32 (*op_rsize_bop)(struct svc_rqst *, struct nfsd4_op *);
+	u32 (*op_rsize_bop)(const struct svc_rqst *rqstp,
+			const struct nfsd4_op *op);
 	void (*op_get_currentstateid)(struct nfsd4_compound_state *,
 			union nfsd4_op_u *);
 	void (*op_set_currentstateid)(struct nfsd4_compound_state *,