net: aquantia: fixups on 64bit dma counters

DMA counters are 64 bit and we can fetch that to reduce
counter overflow, espesially on byte counters.

Tested-by: Nikita Danilov <ndanilov@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: Dmitry Bogdanov <dmitry.bogdanov@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>