MPC5121e ADS PCI support take 3

Adds PCI support for MPC5121

Tested with drivers/net/rtl8139.c

Support is conditional since PCI on old silicon does not work.

ads5121_PCI_config turns on PCI

In this version, condition compilation of PCI code has been moved
from ifdef in board/ads5121/pci.c to board/ads5121/Makefile as
suggested by Jean-Christophe PLAGNIOL-VILLARD

Signed-off-by: John Rigby <jrigby@freescale.com>
diff --git a/include/asm-ppc/global_data.h b/include/asm-ppc/global_data.h
index f9a3d92..205f7ed 100644
--- a/include/asm-ppc/global_data.h
+++ b/include/asm-ppc/global_data.h
@@ -103,6 +103,7 @@
 #if defined(CONFIG_MPC512X)
 	u32 ips_clk;
 	u32 csb_clk;
+	u32 pci_clk;
 #endif /* CONFIG_MPC512X */
 #if defined(CONFIG_MPC8220)
 	unsigned long   bExtUart;