MIPS: ath79: Don't return PCIBIOS_* code from pcibios_enable_device()

pcibios_plat_dev_init() is called from pcibios_enable_device() that
should return normal errnos, not PCIBIOS return codes. In this case the
impact is only cosmetic because PCIBIOS_SUCCESSFUL equals 0 that is
success code with errnos as well. Nonetheless, remove the inconsistency
by replacing the PCIBIOS_SUCCESSFUL with 0.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmal.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/pci/fixup-ath79.c

@@ -9,7 +9,7 @@
 
 int pcibios_plat_dev_init(struct pci_dev *dev)
 {
-	return PCIBIOS_SUCCESSFUL;
+	return 0;
 }
 
 int pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)