cxgb3: Use CAP_SYS_RAWIO for firmware

Otherwise theoretically at least

	CAP_NET_ADMIN
	Reload new firmware
	Wait..
	Firmware patches kernel

So it should be CAY_SYS_RAWIO - not that I suspect this is in fact a
credible attack vector!

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>