sched/topology: Drop memset() from init_rootdomain()

sched/topology: Drop memset() from init_rootdomain()

There are only two callers of init_rootdomain(). One of them passes a
global to it and another one sends dynamically allocated root-domain.

There is no need to memset the root-domain in the first case as the
structure is already reset.

Update alloc_rootdomain() to allocate the memory with kzalloc() and
remove the memset() call from init_rootdomain().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/fc2f6cc90b098040970c85a97046512572d765bc.1492065513.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>