SUNRPC: Make svc_addr's argument a constant

Clean up: Add extra type safety and squelch a few compiler complaints
in upcoming patches.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

include/linux/sunrpc/svc.h

@@ -266,17 +266,17 @@ struct svc_rqst {
 /*
  * Rigorous type checking on sockaddr type conversions
  */
-static inline struct sockaddr_in *svc_addr_in(struct svc_rqst *rqst)
+static inline struct sockaddr_in *svc_addr_in(const struct svc_rqst *rqst)
 {
 	return (struct sockaddr_in *) &rqst->rq_addr;
 }
 
-static inline struct sockaddr_in6 *svc_addr_in6(struct svc_rqst *rqst)
+static inline struct sockaddr_in6 *svc_addr_in6(const struct svc_rqst *rqst)
 {
 	return (struct sockaddr_in6 *) &rqst->rq_addr;
 }
 
-static inline struct sockaddr *svc_addr(struct svc_rqst *rqst)
+static inline struct sockaddr *svc_addr(const struct svc_rqst *rqst)
 {
 	return (struct sockaddr *) &rqst->rq_addr;
 }