CMakeLists.txt file in /hal/tests/TESTS/mbed_hal_fpga_ci_test_shield
directory was non-functional as it used the greentea_add_test macro,
which expects a main.cpp in current directory, but no main.cpp exists
there. I checked with @rajkan01 who confirmed that this CMake file is
serving no purpose and is there erroneously. All tests in subdirectories
of this directory have their own CMakeLists.txt that successfully build
them.