net: aquantia: Fix error handling in aq_pci_probe()

We should check "self->aq_hw" for allocation failure, and also we should
free it on the error paths.

Fixes: 23ee07ad

 ("net: aquantia: Cleanup pci functions module")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>