modules: sysfs - export: taint, coresize, initsize

Recent tools do not want to use /proc to retrieve module information. A few
values are currently missing from sysfs to replace the information available
in /proc/modules.

This adds /sys/module/*/{coresize,initsize,taint} attributes.

TAINT_PROPRIETARY_MODULE (P) and TAINT_OOT_MODULE (O) flags are both always
shown now, and do no longer exclude each other, also in /proc/modules.

Replace the open-coded sysfs attribute initializers with the __ATTR() macro.

Add the new attributes to Documentation/ABI.

Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>