cmake: fix LINK_FLAGS_RELEASE typo

* The variable name was spelt wrong and never took effect.

cmake/gcc_stm32.cmake

@@ -52,7 +52,7 @@ SET(CMAKE_EXE_LINKER_FLAGS_DEBUG "" CACHE INTERNAL "linker flags debug")
 SET(CMAKE_C_FLAGS_RELEASE "-Os -flto" CACHE INTERNAL "c compiler flags release")
 SET(CMAKE_CXX_FLAGS_RELEASE "-Os -flto" CACHE INTERNAL "cxx compiler flags release")
 SET(CMAKE_ASM_FLAGS_RELEASE "" CACHE INTERNAL "asm compiler flags release")
-SET(CMAKE_EXE_LINKER_FLAGS_RELESE "-flto" CACHE INTERNAL "linker flags release")
+SET(CMAKE_EXE_LINKER_FLAGS_RELEASE "-flto" CACHE INTERNAL "linker flags release")
 
 SET(CMAKE_FIND_ROOT_PATH ${TOOLCHAIN_PREFIX}/${TARGET_TRIPLET} ${EXTRA_FIND_PATH})
 SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)