platforms/astbmc: Support PCI slot
platforms/astbmc: Support PCI slot

This reworks PCI stuff for astbmc platform to support PCI slot:

   * The PCI slot is created in slot_table_get_slot_info().
   * There are no platform dependent operations provided to PCI
     slots at current stage.
   * The slot location code is populated accordingly.

Signed-off-by: Gavin Shan <0398910e4f4970259b451f0f9d0686cc5e961b81@linux.vnet.ibm.com>
Reviewed-by: Russell Currey <b5ebcef270cdc73fa0593440445c07a93ae1bccb@russell.cc>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

open-power/skiboot,mikey/skiboot,shenki/skiboot,mikey/skiboot,qemu/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,open-power/skiboot,legoater/skiboot,mikey/skiboot,open-power/skiboot,qemu/skiboot,stewart-ibm/skiboot,shenki/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,stewart-ibm/skiboot,legoater/skiboot,legoater/skiboot,open-power/skiboot,legoater/skiboot,shenki/skiboot,qemu/skiboot,open-power/skiboot