stmmac: pci: Make stmmac_pci_find_phy_addr truly generic

Move the special case for the early Galileo firmware into
quark_default_setup. This allows to use stmmac_pci_find_phy_addr for
non-quark cases.

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>