ethernet: remove random_ether_addr()

random_ether_addr() was the original name of the helper which
was kept for backward compatibility (?) after the rename in
commit 0a4dd594

 ("etherdevice: Rename random_ether_addr
to eth_random_addr").

We have a single random_ether_addr() caller left in tree
while there are 70 callers of eth_random_addr().
Time to drop this define.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20211013205450.328092-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>