MAINTAINERS: dmaengine: Update + Hand over the at_hdmac driver to Ludovic

Hand over the Microchip / Atmel DMA driver handled by at_hdmac driver
to Ludovic who is responsible for the newer at_xdmac driver as well.
Also update the entry name and position to follow company changes.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>