via-velocity: don't annotate MAC registers as packed

On ARM, memory accesses through packed pointers behave in unexpected
ways in GCC releases 4.3 and higher; see https://lkml.org/lkml/2011/2/2/163


for discussion.

In this particular case, 32-bit I/O registers are accessed bytewise,
causing incorrect setting of the DMA address registers which in turn
leads to an error interrupt storm that brings the system to a halt.

Since the mac_regs structure does not need any packing anyway, this patch
simply removes the attribute to fix the issue.

Signed-off-by: Ulrich Hecht <uli@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>