dmaengine: at_hdmac/trivial: rearrange CFG register bits assignment

No modification in CFG register configuration, just rearrange
bits directives to group logically and make it more readable.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>