ENGR00170944 [MX6Q MMC]suspend/resume crash

ENGR00170944 [MX6Q MMC]suspend/resume crash

if the system suspend in the process of data transfer, current request
is broken by the suspend request, thus there're sd/mmc requests error logs.

to prevent this error, add a claim host in suspend function and release it
in resume function to make sure the request is finished before entering suspend
and next request could be started after resuming.

Signed-off-by: Tony Lin <tony.lin@freescale.com>