mtd: nand: denali: support 64bit capable DMA engine

The current driver only supports the DMA engine up to 32 bit
physical address, but there also exists 64 bit capable DMA engine
for this IP.

The data DMA setup sequence is completely different, so I added the
64 bit DMA code as a new function denali_setup_dma64().  The 32 bit
one has been renamed to denali_setup_dma32().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>