powerpc/86xx: fsl_pcibios_fixup_bus requires CONFIG_PCI

Function fsl_pcibios_fixup_bus() is available only if PCI is enabled.  The
MPC8610 HPCD platform file was not protecting the assigned with an #ifdef,
which results in a link failure when PCI is disabled.  Every other platform
already has this #ifdef.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>