mach-exynos: cpufreq: Show list of available frequencies

This patch enables 'scaling_available_frequencies' attribute
showing list of available frequencies.

Change-Id: I9b6ad786ffaaba8ad6fe5aa9045fd793c095b5ae
Merge remote-tracking branch 'cm/cm-11.0' into atr-aosp-cm11

Conflicts:
	arch/arm/mach-exynos/cpufreq.c