mpc83xx: PCI: Fix hard-coded first_busno value

mpc83xx: PCI: Fix hard-coded first_busno value

We should use pci_last_busno() in pci_init_bus(), otherwise we'll
erroneously re-use PCI0's first_busno for PCI1 hoses.

NOTE: The patch is untested. All MPC83xx FSL boards I have have
PCI1 in miniPCI form, for which I don't have any cards handy.

But looking in cpu/mpc85xx/pci.c:
...
#ifdef CONFIG_MPC85XX_PCI2
        hose = &pci_hose[1];

        hose->first_busno = pci_hose[0].last_busno + 1;

And considering that we do the same for MPC83xx PCI-E support,
I think this patch is correct.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>