rockchip: Add core Soc start-up code for rv1108

RV1108 is embedded with an ARM Cortex-A7 single core and a DSP core
from Rockchip. It is designed for varies application scenario such
as car DVR, sports DV, secure camera and UAV camera.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>