Fix vendor include in mainline_arm64.

Include all the _vendor equivalents of the mk's included by
mainline_system. The previous include was a typo.

Bug: 80410283
Test: lunch mainline_arm64; m nothing
Change-Id: I71cf6509ad67ed28908716356228ef3980823bf6
diff --git a/target/product/mainline_arm64.mk b/target/product/mainline_arm64.mk
index 92954db..c83ce5f 100644
--- a/target/product/mainline_arm64.mk
+++ b/target/product/mainline_arm64.mk
@@ -16,7 +16,7 @@
 
 $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/mainline_system.mk)
-$(call inherit-product, $(SRC_TARGET_DIR)/product/base_vendor.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/handheld_vendor.mk)
 
 PRODUCT_NAME := mainline_arm64
 PRODUCT_DEVICE := generic_arm64