m7: post_boot: Set minimum cpufreq frequency

Also set permissions on cpu0's min/max_freq.

A couple of users have commented that sometimes the minimum
frequency is set to the maximum frequency after boot so force
the minimum frequency.

Taken from http://review.cyanogenmod.org/#/c/56036/

Change-Id: Ia2a221348c8a6980090dfbd5e4f859b933da277c
m7-common: post_boot.sh code cleanup (alignment)

Change-Id: I3b4c145dc643153d6b41d1753609f595f6c8d714
Merge remote-tracking branch 'cm/cm-11.0' into HEAD