mmc: sdhci: Fix mmc_power_off sequence

During mmc_power_off in sdhci_do_set_ios clock to the card needs
to be turned off as a last step after the power is turned off.
The existing check turns off the clock first and thereby never
turns off the power.

Change-Id: I961b090c814d9182aff11da7a3b090d9a84fc299
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>