net: remove __get_unaligned_cpu32 from macvlan driver

The __get_unaligned_cpu32 function is deprecated. So, replace it with
the more generic get_unaligned and just cast the input parameter.

Signed-off-by: Julian Vetter <julian@outer-limits.org>
Link: https://patch.msgid.link/20250408091548.2263911-1-julian@outer-limits.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>