mmc: dw_mmc: disable biu clk if possible

We could disable biu clk if gpio card detect available,
or it is a non-removable device.

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>