mmc: sdhci-of-arasan: fix clk issue in sdhci_arasan_remove()

sdhci_pltfm_unregister() could operate host's registers, it will cause
problems if the clk is already disabled and unprepared. Fix this issue
by moving the clk_disable_unprepare() call to the end of remove
function.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>