sched/numa: remove unused code from update_numa_stats()

With :
  commit 2d4056fa ("sched/numa: Remove numa_has_capacity()")

the local variables smt, cpus and capacity and their results are not used
anymore in numa_has_capacity()

Remove this unused code

Cc: Rik van Riel <riel@surriel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1535548752-4434-2-git-send-email-vincent.guittot@linaro.org