ppc: m68k: Move i2c1_clk, i2c2_clk to arch_global_data

Move these fields into arch_global_data and tidy up. This is needed for
both ppc and m68k since they share the i2c driver.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/m68k/cpu/mcf532x/speed.c b/arch/m68k/cpu/mcf532x/speed.c
index cfdcc8b..8efb451 100644
--- a/arch/m68k/cpu/mcf532x/speed.c
+++ b/arch/m68k/cpu/mcf532x/speed.c
@@ -271,7 +271,7 @@
 	gd->cpu_clk = (gd->bus_clk * 3);
 
 #ifdef CONFIG_FSL_I2C
-	gd->i2c1_clk = gd->bus_clk;
+	gd->arch.i2c1_clk = gd->bus_clk;
 #endif
 
 	return (0);