linux-phytec-ti

mmc: dw_mmc: remove setup_clock callback

Now, no dw_mmc variant drivers use this callback, let's
remove it.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>