ARM: imx27, imx5: Add kconfig selects for cpufreq-cpu0

There are some config options not selected by imx27 and imx5 that are
necessary to use the cpufreq-cpu0 driver.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>