stmmac: pci: Make stmmac_pci_info structure constant

By removing the PCI device reference from the structure and passing it
as parameters to the interested functions, we can make quark_pci_info
const.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>