Android.mk: Replace TARGET_PRODUCT with TARGET_BOARD_PLATFORM
This provides the flexibility to use TARGET_BOARD_PLATFORM to maintain
a common codebase while differentiating between products with
TARGET_PRODUCT.
CRs-Fixed: 2955427
Change-Id: I824730142b6a68968c6bb44fec841ed49642ef7a
Signed-off-by: Subash Abhinov Kasiviswanathan <[email protected]>