board: rockchip: Add rk3568 evb support

Add support for rk3568 evaluation board.

Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/Kconfig b/arch/arm/mach-rockchip/Kconfig
index 4a2d35a..35bdef2 100644
--- a/arch/arm/mach-rockchip/Kconfig
+++ b/arch/arm/mach-rockchip/Kconfig
@@ -403,5 +403,6 @@
 source "arch/arm/mach-rockchip/rk3328/Kconfig"
 source "arch/arm/mach-rockchip/rk3368/Kconfig"
 source "arch/arm/mach-rockchip/rk3399/Kconfig"
+source "arch/arm/mach-rockchip/rk3568/Kconfig"
 source "arch/arm/mach-rockchip/rv1108/Kconfig"
 endif