SUNRPC: Mark auth and cred operation tables as constant.

Also do the same for gss_api operation tables.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_gss/gss_spkm3_mech.c b/net/sunrpc/auth_gss/gss_spkm3_mech.c
index 7e15aa6..577d590 100644
--- a/net/sunrpc/auth_gss/gss_spkm3_mech.c
+++ b/net/sunrpc/auth_gss/gss_spkm3_mech.c
@@ -202,7 +202,7 @@
 	return err;
 }
 
-static struct gss_api_ops gss_spkm3_ops = {
+static const struct gss_api_ops gss_spkm3_ops = {
 	.gss_import_sec_context	= gss_import_sec_context_spkm3,
 	.gss_get_mic		= gss_get_mic_spkm3,
 	.gss_verify_mic		= gss_verify_mic_spkm3,