CMake: Clean remnant of experiment with ARM toolchain

The removed code was testing that compiler flags could be added
to the assembler using generator expression. It was not to be
committed.

tools/cmake/toolchains/ARM.cmake

@@ -8,16 +8,9 @@ set(CMAKE_AR "armar")
 set(ARM_ELF2BIN "fromelf")
 set_property(GLOBAL PROPERTY ELF2BIN ${ARM_ELF2BIN})
 
-option(MBEDIDE "Use Arm compiler from Mbed Studio" OFF)
-if(MBEDIDE)
-    set_property(GLOBAL PROPERTY MBED_STUDIO_ARM_COMPILER "--ide=mbed")
-endif()
-
 # Sets toolchain options
 function(mbed_set_toolchain_options target)
-    get_property(mbed_studio_arm_compiler GLOBAL PROPERTY MBED_STUDIO_ARM_COMPILER)
     list(APPEND common_options
-        "${mbed_studio_arm_compiler}"
         "-c"
         "--target=arm-arm-none-eabi"
         "-mthumb"
@@ -44,11 +37,9 @@ function(mbed_set_toolchain_options target)
     target_compile_options(${target}
         INTERFACE
             $<$<COMPILE_LANGUAGE:ASM>:--target=arm-arm-none-eabi -masm=auto>
-            $<$<COMPILE_LANGUAGE:ASM>:${MBED_STUDIO_ARM_COMPILER}>
     )
 
     list(APPEND link_options
-        "${MBED_STUDIO_ARM_COMPILER}"
         "--map"
     )