Filesystem: Move operations to mount table entry

The scope of the file system operations is the file system instance.
The scope of the file system node handlers is the file location.  The
benefit of moving the operations to the mount table entry is a size
reduction of the file location (rtems_filesystem_location_info_t).  The
code size is slightly increased due to additional load instructions.

Restructure rtems_filesystem_mount_table_entry_t to improve cache
efficiency.

cpukit/libfs/src/devfs/devfs_init.c

@@ -56,9 +56,9 @@ int devFS_initialize(
   int rv = 0;
 
   if (data != NULL) {
+    mt_entry->ops = &devFS_ops;
     mt_entry->immutable_fs_info = data;
     mt_entry->mt_fs_root->location.handlers = &devFS_file_handlers;
-    mt_entry->mt_fs_root->location.ops = &devFS_ops;
   } else {
     errno = EINVAL;
     rv = -1;