mmc: sdhci-msm: Use auto suspend instead of sync

With use of sync suspend, driver is going to suspend
in atomic context which is not permitted and leading to
below below stack.

pc : __schedule_bug
lr : __schedule_bug
Call trace:
__schedule_bug
__schedule
schedule
rpm_suspend
__pm_runtime_suspend
mmc_release_host
mmc_put_card
mmc_blk_cqe_complete_rq
mmc_blk_mq_complete
blk_done_softirq

To avoid this use auto suspend.

Change-Id: Ie19c06ba07c8340faefebbde9810e65dc11ec6b2
Signed-off-by: Ram Prakash Gupta <rampraka@codeaurora.org>