ARM: rockchip: drop rk3288 jtag/mmc switch handling

We moved that functionality to a more generic place where it can also
be used for other socs, so drop it from architecture code.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>