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.

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>