Remove create linkfile device/rockchip/.BoardConfig.mk if repo sync.
Create device/rockchip/.target_product link to platform (eg:
rv1126_rv1109) if repo sync.
If the link file device/rockchip/.BoardConfig.mk not exist,
build.sh will enter combo to select Board Config (Default: BoardConfig.mk)
Others, "./build.sh lunch" to switch board config.
Signed-off-by: Weiwen Chen <cww@rock-chips.com>
Change-Id: Ibba692a68f4d5fc4959161dc835178e0b4b6e0e5