It's 1.6 GHz for the Cortex-A15.

Avoids warnings like "/cpus/cpu@0 missing clock-frequency property".
Signed-off-by: NAndreas Faerber <afaerber@suse.de>
Reviewed-by: NTarek Dakhran <t.dakhran@samsung.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>