omni: fix overlay package build

Change-Id: I92b111e79196f072594c5f71a6895771c6378e3c
diff --git a/google/themes/NotificationsPrimary/Android.mk b/google/themes/NotificationsPrimary/Android.mk
index dcced9e..1a80347 100644
--- a/google/themes/NotificationsPrimary/Android.mk
+++ b/google/themes/NotificationsPrimary/Android.mk
@@ -5,7 +5,7 @@
 LOCAL_RRO_THEME := NotificationsPrimary
 LOCAL_CERTIFICATE := platform
 LOCAL_MODULE_TAGS := optional
-LOCAL_SDK_VERSION := 28
+LOCAL_SDK_VERSION := current
 LOCAL_SRC_FILES := $(call all-subdir-java-files)
 LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res