83xx: Replace CONFIG_MPC83XX with CONFIG_MPC83xx

Use the standard lowercase "xx" capitalization that other Freescale
architectures use for CPU defines to prevent confusion and errors

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
diff --git a/doc/README.mpc837xerdb b/doc/README.mpc837xerdb
index 510e3bb..25ea65b 100644
--- a/doc/README.mpc837xerdb
+++ b/doc/README.mpc837xerdb
@@ -52,7 +52,7 @@
 
 	include/configs/MPC837XERDB.h
 
-    CONFIG_MPC83XX	    MPC83xx family for both MPC8349 and MPC8360
+    CONFIG_MPC83xx	    MPC83xx family for both MPC8349 and MPC8360
     CONFIG_MPC837X	    MPC837x specific
     CONFIG_MPC837XERDB	    MPC837xE-RDB board specific