pci: Add ability to re-enumerate PCI buses

Add a new 'pci enum' command which re-enumerates the PCI buses.  This
command is enabled via the CONFIG_CMD_PCI_ENUM define and can be useful
in boards with FPGAs connected via PCI/PCIe, boards that support PCI
hot-plugging, or during PCI debug.

Also enable the 'pci enum' command for X-ES's Freescale-based boards.

Signed-off-by: John Schmoller <jschmoller@xes-inc.com>
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Wolfgang Denk <wd@denx.de>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cd64a87..848746f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -139,7 +139,7 @@
  *
  */
 
-static struct pci_controller* hose_head = NULL;
+static struct pci_controller* hose_head;
 
 void pci_register_hose(struct pci_controller* hose)
 {
@@ -640,6 +640,8 @@
 	}
 #endif /* CONFIG_PCI_BOOTDELAY */
 
+	hose_head = NULL;
+
 	/* now call board specific pci_init()... */
 	pci_init_board();
 }