run-cppcheck: use TFM_TOOLCHAIN_FILE instead of CMAKE_TOOLCHAIN_FILE

CMAKE_TOOLCHAIN_FILE is deprecated in favor of TFM_TOOLCHAIN_FILE.
In addition, TFM_TOOLCHAIN_FILE does accept relative paths.

This changes only get rid of the deprecation warning:

CMake Deprecation Warning at CMakeLists.txt:41 (message):
  SETTING CMAKE_TOOLCHAIN_FILE is deprecated.  It has been replaced with
  TFM_TOOLCHAIN_FILE.

CMake Deprecation Warning at CMakeLists.txt:42 (message):
  INTERPRETING -DCMAKE_TOOLCHAIN_FILE=toolchain_GNUARM.cmake as
  -DTFM_TOOLCHAIN_FILE=toolchain_GNUARM.cmake

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
Change-Id: I0395ea45815644d1657ab6b9c64c1df730806da7
diff --git a/run-cppcheck.sh b/run-cppcheck.sh
index 0723204..66de5e7 100755
--- a/run-cppcheck.sh
+++ b/run-cppcheck.sh
@@ -80,7 +80,7 @@
 echo
 echo '******* Generating compile_commands.json ***************'
 echo
-generate_project $(fix_win_path $(get_full_path ./)) "./" "cppcheck" "-DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DTFM_PLATFORM=mps2/an521 -DCMAKE_TOOLCHAIN_FILE=toolchain_GNUARM.cmake"
+generate_project $(fix_win_path $(get_full_path ./)) "./" "cppcheck" "-DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DTFM_PLATFORM=mps2/an521 -DTFM_TOOLCHAIN_FILE=toolchain_GNUARM.cmake"
 
 #Enter the build directory
 bdir=$(make_build_dir_name "./" "cppcheck")