Enable CPUidle so it's easier for maintainers to notice
if some future code changes cause regressions.
Cc: Kevin Hilman <khilman@linaro.org> Cc: Nishanth Menon <nm@ti.com> Cc: Paul Walmsley <paul@pwsan.com> Cc: Tero Kristo <t-kristo@ti.com> Signed-off-by: Tony Lindgren <tony@atomide.com>