[POWERPC] mpc5200: Add common mpc52xx_setup_pci() routine

This patch moves a generic pci init code from lite5200
platform file to a common mpc52xx_setup_pci() routine
and adds additional compatibility property verification.

Signed-off-by: Marian Balakowicz <m8@semihalf.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>