qcom-common: init: set permissions for interactive's timer_rate
logging would show:
    E/CM PowerHAL(  635): Error opening /sys/devices/system/cpu/cpufreq/interactive/timer_rate: Permission denied
give timer_rate proper permission on init to allow powerhal access
Signed-off-by: Luis Cruz <ljc2491@gmail.com>

Change-Id: I7a6c2e323a642ec1384581eb9b8b53cb3a8d3259