Mark version as 1.6.1-rc

Change-Id: I3d28433f84d7c9503b76b148fe272f6aa873c012
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/Makefile b/Makefile
index e0f1463..1911e7e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,8 @@
 VERSION_MAJOR 	   = 1
 VERSION_MINOR 	   = 6
-PATCHLEVEL 	   = 0
+PATCHLEVEL 	   = 1
 VERSION_RESERVED   = 0
-EXTRAVERSION       =
+EXTRAVERSION       = rc
 NAME 		   = Zephyr Kernel
 
 export SOURCE_DIR PROJECT MDEF_FILE