dma/cnxk: add scatter-gather copy
dma/cnxk: add scatter-gather copy

Add the copy_sg function that will do the multiple DMA transfers of
different sizes and different source/destination as well.

Signed-off-by: Radha Mohan Chintakuntla <4fe9466f2319f8c0a1d2764319802078e8dc052e@marvell.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk