rockchip: rk3328: add soc basic support

RK3328 is a SoC from Rockchip with quad-core Cortex-A53 CPU.
It supports two USB2.0 EHCI ports. Other interfaces are very
much like RK3288, the DRAM are 32bit width address and support
address from 0 to 4GB-16MB range.

Signed-off-by: William Zhang <william.zhang@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
Add empty arch/arm/mach-rockchip/rk3328/Kconfig to avoid build error:
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-rockchip/Makefile b/arch/arm/mach-rockchip/Makefile
index 151fa2d..6b251c7 100644
--- a/arch/arm/mach-rockchip/Makefile
+++ b/arch/arm/mach-rockchip/Makefile
@@ -28,4 +28,5 @@
 endif
 
 obj-$(CONFIG_ROCKCHIP_RK3288) += rk3288/
+obj-$(CONFIG_ROCKCHIP_RK3328) += rk3328/
 obj-$(CONFIG_ROCKCHIP_RK3399) += rk3399/