sky2: copy received packets on inefficient unaligned architecture

Modified from original patch from Chris.

The sky2 driver has to have 8 byte alignment of receive buffer
on some chip versions. On architectures which don't support efficient
unaligned access this doesn't work very well. The solution is to
just copy all received packets which is what the driver already
does for small packets.

This allows the driver to be used on the Tilera TILEmpower-Gx, since
the tile architecture doesn't currently handle kernel unaligned accesses,
just userspace.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>