net: lan78xx: Merge memcpy + lexx_to_cpus to get_unaligned_lexx

Merge the combo use of memcpy and lexx_to_cpus.
Use get_unaligned_lexx instead.
This simplifies the code.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Acked-by: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>