Up C++ version to 14 for arm-none-eabi-gcc

Change-Id: I587f70020cf8cfaf764d4f0e08e920141a52c327
diff --git a/cmake/toolchain/arm-none-eabi-gcc.cmake b/cmake/toolchain/arm-none-eabi-gcc.cmake
index 8a4ac20..7b7dac2 100644
--- a/cmake/toolchain/arm-none-eabi-gcc.cmake
+++ b/cmake/toolchain/arm-none-eabi-gcc.cmake
@@ -33,7 +33,7 @@
 SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 
 set(CMAKE_C_STANDARD 99)
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 14)
 
 # The system processor could for example be set to cortex-m33+nodsp+nofp.
 set(__CPU_COMPILE_TARGET ${CMAKE_SYSTEM_PROCESSOR})