please test - AR5416/AR9220 PCI on SMP fix

Hi,

I've included a fix into our ath/hal driver which enforces serialised
register access on AR5416 and later PCI NICs when running on an SMP
system.
This is needed to fix a system hang issue that occurs with multiple
CPUs doing register IO to/from these devices. I don't have any further
information then that.

Please update to -head and give things a try. If it still hangs when
you bring the interface up, please email me a boot dmesg so I can
ensure that it's enabled.
You can also enable it manually before you create the interface -
sysctl dev.ath.X.hal.serialise_reg_war=1 .

Thanks,


Adrian