sm8350-common: Pass TARGET_PRODUCT variable to kernel flags

This is used by audio techpack

Change-Id: I508442db6b8172510eb72ae9733c7903350df940

BoardConfigCommon.mk

@@ -91,7 +91,10 @@ KERNEL_LD := LD=ld.lld
 BOARD_BOOT_HEADER_VERSION := 3
 BOARD_MKBOOTIMG_ARGS += --header_version $(BOARD_BOOT_HEADER_VERSION)
 
-TARGET_KERNEL_ADDITIONAL_FLAGS := DTC_EXT=$(shell pwd)/prebuilts/misc/linux-x86/dtc/dtc LLVM=1
+TARGET_KERNEL_ADDITIONAL_FLAGS := \
+    DTC_EXT=$(shell pwd)/prebuilts/misc/linux-x86/dtc/dtc \
+    LLVM=1 \
+    TARGET_PRODUCT=$(PRODUCT_DEVICE)
 TARGET_KERNEL_CLANG_COMPILE := true
 TARGET_KERNEL_SOURCE := kernel/xiaomi/sm8350