omni: add property ro.omni.branch

used by OmniChange

TODO: would be very nice if the value could be calculated
instead of hardcoded

Change-Id: I4369fa92d02dab10badb8fc861de4b2b9d66d2df
diff --git a/config/version.mk b/config/version.mk
index 044fb0b..ac6e17c 100644
--- a/config/version.mk
+++ b/config/version.mk
@@ -24,8 +24,11 @@
     ROM_VERSION := $(PLATFORM_VERSION)-$(shell date +%Y%m%d)-$(TARGET_PRODUCT_SHORT)-$(ROM_BUILDTYPE)
 endif
 
+ROM_BRANCH := android-12.0
+
 # Apply it to build.prop
 PRODUCT_PRODUCT_PROPERTIES += \
     ro.modversion=OmniROM-$(ROM_VERSION) \
     ro.omni.version=$(ROM_VERSION) \
-    ro.omni.device=$(TARGET_PRODUCT_SHORT)
+    ro.omni.device=$(TARGET_PRODUCT_SHORT) \
+    ro.omni.branch=$(ROM_BRANCH)