net: ALIGN/PTR_ALIGN cleanup in alloc_netdev_mq()/netdev_priv()

Use ALIGN() and PTR_ALIGN() macros instead of handcoding them.

Get rid of NETDEV_ALIGN_CONST ugly define

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>