Fix linker config file processing logic for O-MR1

Since ld.config.VER.txt files are not versioned, ${VNDK_VER}
previously appended to the VNDK directories is replaced with
the actual VER number.

Test: python update.py 27 --branch oc-mr1-treble-dev
--build 4546415
Bug: 70603313

Change-Id: Ibb7acae183b355529bb83e8860277f453f01ffe3