net: axi_emac: Convert to ofnode functions

FDT functions is not working when OF_LIVE is enabled.
Convert fdt parsing functions to ofnode parsing functions.

Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Link: https://lore.kernel.org/r/20230811074351.26916-1-fido_max@inbox.ru