ppc/85xx: Move to using fsl_setup_hose on MPC8572 DS

We can use fsl_setup_hose to determine if we are a agent/end-point or
a host.  Rather than using some SoC specific register we can just look
at the PCI cfg space of the host controller to determine this.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>