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/cpu/mpc5xxx/ide.c b/arch/powerpc/cpu/mpc5xxx/ide.c
index d337abb..094f62b 100644
--- a/arch/powerpc/cpu/mpc5xxx/ide.c
+++ b/arch/powerpc/cpu/mpc5xxx/ide.c
@@ -75,7 +75,7 @@
 	psdma->PtdCntrl |= 1;
 
 	/* Init timings : we use PIO mode 0 timings */
-	period = 1000000000 / gd->ipb_clk;	/* period in ns */
+	period = 1000000000 / gd->arch.ipb_clk;	/* period in ns */
 
 	t0 = CALC_TIMING (600);
 	t2_8 = CALC_TIMING (290);