ENGR00220469 mmc: sdio: claim host on suspend and release on resuming

ENGR00220469 mmc: sdio: claim host on suspend and release on resuming

issue:
Since there's no sync mechanism between sdio bus suspending and sdio_irq_thread,
it will cause that sdio_irq_thread still makes sdhc request even after sdio bus
suspends.

fix:
On suspending sdio bus, claim host, so that:
1. mmc_sdio_suspend will wait for finishing of sdio_irq_thread.
2. sdio_irq_thread will be blocked even being scheduled.
And release host on resuming.

Acked-by: Aisheng DONG <b29396@freescale.com>
Signed-off-by: Ryan QIAN <b32804@freescale.com>