CMake: Remove undefined functions

The function mbed_set_mbed_target_linker_script no longer exists. This
commit removes the call to this function from the application
CMakeLists.txt.

mbed_configure_app_target has also been deprecated. Remove it.

Author: rwalton-arm

CMakeLists.txt

@@ -13,10 +13,6 @@ add_subdirectory(${MBED_PATH})
 
 add_executable(${APP_TARGET})
 
-mbed_configure_app_target(${APP_TARGET})
-
-mbed_set_mbed_target_linker_script(${APP_TARGET})
-
 project(${APP_TARGET})
 
 target_include_directories(${APP_TARGET}