module: add /sys/module/<name>/uevent files

Userspace wants to manage module parameters with udev rules.
This currently only works for loaded modules, but not for
built-in ones.

To allow access to the built-in modules we need to
re-trigger all module load events that happened before any
userspace was running. We already do the same thing for all
devices, subsystems(buses) and drivers.

This adds the currently missing /sys/module/<name>/uevent files
to all module entries.

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