MPC512X: Fixed typo in macro name.

Signed-off-by: Grzegorz Bernacki <gjb@semihalf.com>
diff --git a/include/common.h b/include/common.h
index 9ef9344..54083f1 100644
--- a/include/common.h
+++ b/include/common.h
@@ -468,7 +468,7 @@
 #elif defined(CONFIG_MPC5xxx)
 int	prt_mpc5xxx_clks (void);
 #endif
-#if defined(CONFIG_MPC512x)
+#if defined(CONFIG_MPC512X)
 int	prt_mpc512xxx_clks (void);
 #endif
 #if defined(CONFIG_MPC8220)