powerpc/booke: Simplify the MPC85XX PCIe root complex driver

[jhibbits]

Summary

Due to bugs in the enumeration code, fsl_pcib_init() was not configuring
sub-bridges properly, so devices hanging off a separate bridge would not
be found. Since the generic PCI code already supports probing child
buses, just delete this code and initialize only the device itself,
letting the generic code handle all the additional probing and
initializing.

[jhibbits]

Remove MSI bits

[bdragon]

Tested previously on GCC4 kernel on X5000.

Tested on clang kernel on X5000 (now that clang kernel is working).

sys/powerpc/mpc85xx/pci_mpc85xx.c

324

Slight conflict -- HEAD is missing ipreg here.

[bdragon]

sys/powerpc/mpc85xx/pci_mpc85xx.c

324

yeah, both this and D22014 mess with the same line.