kobject: Add helper kobj_ns_type_is_valid()

There are too many "(type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES)"
and "(type <= KOBJ_NS_TYPE_NONE) || (type >= KOBJ_NS_TYPES)", add helper
kobj_ns_type_is_valid() to eliminate duplicate code and improve
readability.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20230726062508.950-1-thunder.leizhen@huaweicloud.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>