sched/fair: Change "has_capacity" to "has_free_capacity"

The capacity of a CPU/group should be some intrinsic value that doesn't
change with task placement.  It is like a container which capacity is
stable regardless of the amount of liquid in it (its "utilization")...
unless the container itself is crushed that is, but that's another story.

Therefore let's rename "has_capacity" to "has_free_capacity" in order to
better convey the wanted meaning.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linaro-kernel@lists.linaro.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-djzkk027jm0e8x8jxy70opzh@git.kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>