module: change attr callbacks to take struct module_kobject

This simplifies the next patch, where we have an attribute on a
builtin module (ie. module == NULL).

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (split into 2)

diff --cc include/linux/module.h
Simple merge

diff --cc kernel/module.c
Simple merge

diff --cc kernel/params.c
Simple merge