sun7i: Put the CPU in smp mode when starting (the non spl) u-boot

If the CPU is left in AMP mode, all its caches are disabled. This fixes the
circa 8 second delay when uncompressing the Linux uImage on boot.

Thanks to Maxime Ripard for pointing out this bit needs to be set.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>