Auto Option: Access SD device in DMA mode if controller supports
it, otherwise in PIO mode.
ADMA Option: Access Advanced DMA Transfer mode
SDMA Option: Access Single Operation DMA Transfer mode
DMA Option: Access SD device in DMA mode.
PIO Option: Access SD device in PIO mode.
Note: for detailed description of these transfer modes please refer
to the SD Host Controller Simplified Specification Version 2.00