The driver support single core and multi core ARM SoCs. For multi core,
it assume all cores share the same clock and voltage.

Changes in v2:
 - add volatage change support
 - change '_' in property name to '-'
 - use initial value to calculate loops_per_jiffy
 - fix reading cpu_volts property bug 
 - let cpufreq_frequency_table_cpuinfo routines handle cpu_freq_khz_max/min
 - don't change freq in arm_cpufreq_exit, because every core share the same freq.
 - use unsigned long describe frequency as much as possible. Because clk use
   unsigned long, but cpufreq use unsigned int.

[PATCH V2 1/4] cpufreq: add arm soc generic cpufreq driver
[PATCH V2 2/4] dts/imx6q: add cpufreq property
[PATCH V2 3/4] arm/imx6q: register arm_clk as cpu to clkdev
[PATCH V2 4/4] arm/imx6q: select ARCH_HAS_CPUFREQ

Thanks
Richard