dt-bindings: rockchip-dw-mshc: add RK1108 dw-mshc description

Add "rockchip,rk1108-dw-mshc", "rockchip,rk3288-dw-mshc" for
dwmmc on rk1108 platform.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>