net: axi_emac: Use reg property for DMA registers

As per the xlnx,axi-ethernet-1.00.a DT documentation in linux, the AXI
DMA registers can be obtained via the reg property or via a separate
node for the axistream DMA controller. Currently only the latter is
supported, so add support to fetch the DMA controller registers from the
"reg" property.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20231116164024.139934-1-mchitale@ventanamicro.com


Signed-off-by: Michal Simek <michal.simek@amd.com>