omap4-common: fix permissions for cpufreq/scaling_min_freq

this allow mediaserver to enable performance mode for OMAP4 USB Audio
which was overridden by init.cm.rc

Change-Id: Ie8be95b20786685708cb8a49c14d08454f2051dd
Merge branch 'cm-11.0' of https://github.com/Atrix2-Dev-Team/android_device_motorola_edison into cm-11.0