Rename namespace configuration source files.

For strict VNDK runtime restriction, use ld.config.txt as a source
file. For treblized devices without BOARD_VNDK_VERSION, use
ld.config.vndk_lite.txt file.

Test: Build and boot on Pixel 2017 and 2018 devices.
Change-Id: Ie5b77facd4c11bc73219ecf13ad1298ac5d60d8e