CMake: greentea: Remove call to deprecated function
CMake: greentea: Remove call to deprecated function

mbed_greentea::mbed_greentea_add_test was calling the deprecated
`mbed_configure_app_target` function, which is currently a no-op.

mbedmicro/mbed,mbedmicro/mbed,mbedmicro/mbed,mbedmicro/mbed,mbedmicro/mbed