SUNRPC: Make trace_svc_process() display the RPC procedure symbolically

The next few patches will employ these strings to help make server-
side trace logs more human-readable. A similar technique is already
in use in kernel RPC client code.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 79ff172..c5348ba 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -1060,6 +1060,7 @@ static const struct svc_procedure nfs4_callback_procedures1[] = {
 		.pc_decode = nfs4_decode_void,
 		.pc_encode = nfs4_encode_void,
 		.pc_xdrressize = 1,
+		.pc_name = "NULL",
 	},
 	[CB_COMPOUND] = {
 		.pc_func = nfs4_callback_compound,
@@ -1067,6 +1068,7 @@ static const struct svc_procedure nfs4_callback_procedures1[] = {
 		.pc_argsize = 256,
 		.pc_ressize = 256,
 		.pc_xdrressize = NFS4_CALLBACK_BUFSIZE,
+		.pc_name = "COMPOUND",
 	}
 };