Prepare for 1.3.1-rc1

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/Makefile b/Makefile
index bfd4132..db3d1e8 100644
--- a/Makefile
+++ b/Makefile
@@ -23,8 +23,8 @@
 
 VERSION = 1
 PATCHLEVEL = 3
-SUBLEVEL = 0
-EXTRAVERSION =
+SUBLEVEL = 1
+EXTRAVERSION = -rc1
 U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
 VERSION_FILE = $(obj)include/version_autogenerated.h