ppc: Move mpc5xxx clocks to arch_global_data

Move ipb_clk and pci_clk into arch_global_data and tidy up.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/lib/board.c b/arch/powerpc/lib/board.c
index 22bd713..63118a3 100644
--- a/arch/powerpc/lib/board.c
+++ b/arch/powerpc/lib/board.c
@@ -589,7 +589,7 @@
 	bd->bi_ipsfreq = gd->ips_clk;
 #endif /* CONFIG_MPC512X */
 #if defined(CONFIG_MPC5xxx)
-	bd->bi_ipbfreq = gd->ipb_clk;
+	bd->bi_ipbfreq = gd->arch.ipb_clk;
 	bd->bi_pcifreq = gd->pci_clk;
 #endif /* CONFIG_MPC5xxx */
 	bd->bi_baudrate = gd->baudrate;	/* Console Baudrate     */