kobject: Make support for uevent_helper optional.

Support for uevent_helper, aka hotplug, is not required on many systems
these days but it can still be enabled via sysfs or sysctl.

Reported-by: Darren Shepherd <darren.s.shepherd@gmail.com>
Signed-off-by: Michael Marineau <mike@marineau.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/base/Kconfig
Simple merge

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

diff --cc kernel/ksysfs.c
Simple merge

diff --cc kernel/sysctl.c
Simple merge

diff --cc lib/kobject_uevent.c
Simple merge