CMakeLists.txt: remove deprecated function call

The function `mbed_configure_app_target()` has been deprecated and
will be eventually removed.

Author: LDong-Arm

CMakeLists.txt

@@ -13,8 +13,6 @@ add_subdirectory(${MBED_PATH})
 
 add_executable(${APP_TARGET})
 
-mbed_configure_app_target(${APP_TARGET})
-
 project(${APP_TARGET})
 
 target_sources(${APP_TARGET}