NFS: Constify mount argument match tables

The mount argument match tables should never be altered so constify them.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/fs_context.c

@@ -199,7 +199,7 @@ enum {
 	Opt_lookupcache_err
 };
 
-static match_table_t nfs_lookupcache_tokens = {
+static const match_table_t nfs_lookupcache_tokens = {
 	{ Opt_lookupcache_all, "all" },
 	{ Opt_lookupcache_positive, "pos" },
 	{ Opt_lookupcache_positive, "positive" },
@@ -215,7 +215,7 @@ enum {
 	Opt_local_lock_err
 };
 
-static match_table_t nfs_local_lock_tokens = {
+static const match_table_t nfs_local_lock_tokens = {
 	{ Opt_local_lock_all, "all" },
 	{ Opt_local_lock_flock, "flock" },
 	{ Opt_local_lock_posix, "posix" },
@@ -231,7 +231,7 @@ enum {
 	Opt_vers_err
 };
 
-static match_table_t nfs_vers_tokens = {
+static const match_table_t nfs_vers_tokens = {
 	{ Opt_vers_2, "2" },
 	{ Opt_vers_3, "3" },
 	{ Opt_vers_4, "4" },