mmc: core: return an error on suspend if mmc_deselect_cards fails

When mmc_host is not spi mode, mmc/sd is doing mmc_deselect_cards().
mmc_deselect_cards could be returned error.
If returned error, we can know something wrong when enter suspend.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>