omni: change default to name images with local date

and not UTC - old behaviur can still be achieved with
setting ROM_BUILDTIME_UTC

Change-Id: I1c2239e88733afe7140d09d80d060195dff92462
diff --git a/config/version.mk b/config/version.mk
index e2d8d41..6b5201a 100644
--- a/config/version.mk
+++ b/config/version.mk
@@ -24,10 +24,10 @@
 ifdef BUILDTYPE_RELEASE
     ROM_VERSION := $(PLATFORM_VERSION)-$(TARGET_PRODUCT_SHORT)
 else
-ifeq ($(ROM_BUILDTIME_LOCAL),y)
-    ROM_VERSION := $(PLATFORM_VERSION)-$(shell date +%Y%m%d-%H%M%z)-$(TARGET_PRODUCT_SHORT)-$(ROM_BUILDTYPE)
-else
+ifeq ($(ROM_BUILDTIME_UTC),y)
     ROM_VERSION := $(PLATFORM_VERSION)-$(shell date -u +%Y%m%d)-$(TARGET_PRODUCT_SHORT)-$(ROM_BUILDTYPE)
+else
+    ROM_VERSION := $(PLATFORM_VERSION)-$(shell date +%Y%m%d)-$(TARGET_PRODUCT_SHORT)-$(ROM_BUILDTYPE)
 endif
 endif