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/serial.c b/arch/powerpc/cpu/mpc5xxx/serial.c
index eb14161..1ccb4e3 100644
--- a/arch/powerpc/cpu/mpc5xxx/serial.c
+++ b/arch/powerpc/cpu/mpc5xxx/serial.c
@@ -89,7 +89,7 @@
 
 	/* select clock sources */
 	psc->psc_clock_select = 0;
-	baseclk = (gd->ipb_clk + 16) / 32;
+	baseclk = (gd->arch.ipb_clk + 16) / 32;
 
 	/* switch to UART mode */
 	psc->sicr = 0;
@@ -169,7 +169,7 @@
 	volatile struct mpc5xxx_psc *psc = (struct mpc5xxx_psc *)dev_base;
 	unsigned long baseclk, div;
 
-	baseclk = (gd->ipb_clk + 16) / 32;
+	baseclk = (gd->arch.ipb_clk + 16) / 32;
 
 	/* set up UART divisor */
 	div = (baseclk + (gd->baudrate/2)) / gd->baudrate;