uevent: mv uevent_helper into kobject_uevent.c

Move both uevent_helper table into lib/kobject_uevent.c. Place the
registration early in the initcall order with postcore_initcall.

This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.

Signed-off-by: Joel Granados <joel.granados@kernel.org>

kernel/sysctl.c

@@ -1474,15 +1474,6 @@ static const struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-#endif
-#ifdef CONFIG_UEVENT_HELPER
-	{
-		.procname	= "hotplug",
-		.data		= &uevent_helper,
-		.maxlen		= UEVENT_HELPER_PATH_LEN,
-		.mode		= 0644,
-		.proc_handler	= proc_dostring,
-	},
 #endif
 	{
 		.procname	= "overflowuid",