mmc: core: resolve dead lock problem in pm_notify

mmc: core: resolve dead lock problem in pm_notify

BZ 2106

when pm_suspend() is called, in mmc_pm_notify() it will call mmc_claim_host(),
in host->bus_ops->remove(host), that is mmc_sd_remove(), at last it will
call mmc_cleanup_queue(), suspend thread will wait the mmcqd/2 thread to stop,
but in mmcqd/2 thread, mmc_blk_issue_rw_rq() will call mmc_clain_host(),
mmcqd/2 thread will wait in mmc_clain_host(), it will cause dead lock.

Change-Id: I05462d71066c4182ab01934fe64a87957ab47c6a
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>