ARM: mvebu: use the cpufreq-dt platform_data for independent clocks

This commit adjusts the registration of the cpufreq-dt driver in the
mvebu platform to indicate to the cpufreq driver that the platform has
independent clocks for each CPU.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>