net: aquantia: Limit number of MSIX irqs to the number of cpus

There is no much practical use from having MSIX vectors more that number
of cpus, thus cap this first with preconfigured limit, then with number
of cpus online.

Signed-off-by: Pavel Belous <pavel.belous@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>