avr32: Fix cpufreq oops when ondemand governor is default

Move the AP7 cpufreq init to late_initcall() so that we don't try to
bring up cpufreq until the governor is ready. x86 also uses
late_initcall() for this.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>