Staging: goldfish: goldfish_nand: Add DMA Support using dmam_alloc_coherent
Function nand_setup_cmd_params has 2 goals-
-Initialize the cmd_params field so that it can be used to send and read
commands from the device.
-Get a bus address for the allocated memory to transfer to the device.
Replace the combination of devm_kzalloc and _pa() with dmam_alloc_coherent.
Coherent mapping guarantees that the device and CPU are in sync.