release: Zephyr 1.9.0

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/Makefile b/Makefile
index c8c1a10..4e4a13f 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
 VERSION_MINOR 	   = 9
 PATCHLEVEL 	   = 0
 VERSION_RESERVED   = 0
-EXTRAVERSION       = -rc4
+EXTRAVERSION       =
 NAME 		   = Zephyr Kernel
 
 export SOURCE_DIR PROJECT