Allow reading of cpufreq attributes

 * Various tools might want to use these values without writing to
   them. Set world readable for all nodes.

So maybe this fix the issue with Overclock

Change-Id: I519c5a4008e9b0b25fc7f9d9bda926a94d3cd898
Signed-off-by: Carlos Jesús <xxx.reptar.rawrr.xxx@gmail.com>