Use product instead of oem for Product specific module

Bug: 64195575
Test: succeeded building product.img with BOARD_PRODUCTIMAGE_PARTITION_SIZE,
BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE and PRODUCT_PRODUCT_VERITY_PARTITION.
Change-Id: Icc4f8c16bc389fe20db680849f311d02df1299c3
diff --git a/android/androidmk.go b/android/androidmk.go
index 704b560..0ea7564 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -237,7 +237,7 @@
 			fmt.Fprintln(&data.preamble, "LOCAL_ODM_MODULE := true")
 		}
 		if Bool(amod.commonProperties.Product_specific) {
-			fmt.Fprintln(&data.preamble, "LOCAL_OEM_MODULE := true")
+			fmt.Fprintln(&data.preamble, "LOCAL_PRODUCT_MODULE := true")
 		}
 		if amod.commonProperties.Owner != nil {
 			fmt.Fprintln(&data.preamble, "LOCAL_MODULE_OWNER :=", *amod.commonProperties.Owner)