sched: clean up code under CONFIG_FAIR_GROUP_SCHED

With the view of supporting user-id based fair scheduling (and not just
container-based fair scheduling), this patch renames several functions
and makes them independent of whether they are being used for container
or user-id based fair scheduling.

Also fix a problem reported by KAMEZAWA Hiroyuki (wrt allocating
less-sized array for tg->cfs_rq[] and tf->se[]).

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/init/Kconfig b/init/Kconfig
index 11c6762..ef90a15 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -282,13 +282,12 @@
 	  Say N if unsure.
 
 config FAIR_GROUP_SCHED
-	bool "Fair group scheduler"
-	depends on EXPERIMENTAL && CONTAINERS
+	bool "Fair group cpu scheduler"
+	default n
+	depends on EXPERIMENTAL
 	help
-	  This option enables you to group tasks and control CPU resource
-	  allocation to such groups.
-
-	  Say N if unsure.
+	  This feature lets cpu scheduler recognize task groups and control cpu
+	  bandwidth allocation to such task groups.
 
 config SYSFS_DEPRECATED
 	bool "Create deprecated sysfs files"