sunxi: Add CPUCFG debug lock and sun7i cpu power controls

CPUCFG has an unlisted debug control register, which is used to disable
external debug access.

Also, sun7i secondary core power controls are in CPUCFG, as there's no
separate PRCM block.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>