modpost: rename variables in handle_moddevtable()

This commit renames the variables in handle_moddevtable() as follows:

    name       -> type
    namelen    -> typelen
    identifier -> name

These changes align with the definition in include/linux/module.h:

  extern typeof(name) __mod_##type##__##name##_device_table

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>