Implement suspend/resume for mmc and mmcsd drivers.
Now it is possible to suspend/resume with inserted and active card.

To reinitialize card on resume and to detect card change while suspended,
implement bus rescan routines. It can also be used by controllers without
card presence detection signals or with multiple cards per slot support.

While there, cleanup msleep() usage. We have no any rights to exit without
"request done" signal from driver as it could lead to modify after free.