ANDROID: sched: Add Kconfig option DEFAULT_USE_ENERGY_AWARE to set ENERGY_AWARE feature flag

The ENERGY_AWARE sched feature flag cannot be set unless
CONFIG_SCHED_DEBUG is enabled.

So this patch allows the flag to default to true at build time
if the config is set.

Change-Id: I8835a571fdb7a8f8ee6a54af1e11a69f3b5ce8e6
Signed-off-by: John Stultz <john.stultz@linaro.org>