NFSD: Use new __string_len C macros for nfsd_clid_class

Clean up.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/trace.h

@@ -606,7 +606,7 @@ DECLARE_EVENT_CLASS(nfsd_clid_class,
 		__array(unsigned char, addr, sizeof(struct sockaddr_in6))
 		__field(unsigned long, flavor)
 		__array(unsigned char, verifier, NFS4_VERIFIER_SIZE)
-		__dynamic_array(char, name, clp->cl_name.len + 1)
+		__string_len(name, name, clp->cl_name.len)
 	),
 	TP_fast_assign(
 		__entry->cl_boot = clp->cl_clientid.cl_boot;
@@ -616,8 +616,7 @@ DECLARE_EVENT_CLASS(nfsd_clid_class,
 		__entry->flavor = clp->cl_cred.cr_flavor;
 		memcpy(__entry->verifier, (void *)&clp->cl_verifier,
 		       NFS4_VERIFIER_SIZE);
-		memcpy(__get_str(name), clp->cl_name.data, clp->cl_name.len);
-		__get_str(name)[clp->cl_name.len] = '\0';
+		__assign_str_len(name, clp->cl_name.data, clp->cl_name.len);
 	),
 	TP_printk("addr=%pISpc name='%s' verifier=0x%s flavor=%s client=%08x:%08x",
 		__entry->addr, __get_str(name),