arm64: mm: define NET_IP_ALIGN to 0

arm64: mm: define NET_IP_ALIGN to 0

On arm64, there is no need to add 2 bytes of padding to the start of
each network buffer just to make the IP header appear 32-bit aligned.

Since this might actually adversely affect DMA performance some
platforms, let's override NET_IP_ALIGN to 0 to get rid of this
padding.

Acked-by: Ilias Apalodimas <[email protected]>
Tested-by: Ilias Apalodimas <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Acked-by: Will Deacon <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>