net: stmmac: fix "snps,axi-config" node property parsing

net: stmmac: fix "snps,axi-config" node property parsing

In dt-binding snps,dwmac.yaml, some properties under "snps,axi-config"
node are named without "axi_" prefix, but the driver expects the
prefix. Since the dt-binding has been there for a long time, we'd
better make driver match the binding for compatibility.

Fixes: 2c11d8a89f0b ("stmmac: rework DMA bus setting and introduce new platform AXI structure")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20221202161739.2203-1-jszhang@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>