Fix cmake CMAKE_SYSTEM_PROCESSOR string matches

To avoid unwanted matches of regexps, example: "cortex-m3" matches
string "cortex-m33", several string MATCHES have been reworked.

Change-Id: Ifa7982d82a8f02154f373b1c6f058aa98c6ad3e0
diff --git a/cmake/toolchain/arm-none-eabi-gcc.cmake b/cmake/toolchain/arm-none-eabi-gcc.cmake
index 182643f..093005e 100644
--- a/cmake/toolchain/arm-none-eabi-gcc.cmake
+++ b/cmake/toolchain/arm-none-eabi-gcc.cmake
@@ -58,16 +58,16 @@
     --specs=nosys.specs)
 
 # Set floating point unit
-if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "\\+fp")
+if(CMAKE_SYSTEM_PROCESSOR MATCHES "\\+fp")
     set(FLOAT hard)
-elseif(${CMAKE_SYSTEM_PROCESSOR} MATCHES "\\+nofp")
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "\\+nofp")
     set(FLOAT soft)
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m33" OR
-       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m55" OR
-       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m85")
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m33(\\+|$)" OR
+       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m55(\\+|$)" OR
+       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m85(\\+|$)")
     set(FLOAT hard)
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m4" OR
-       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m7")
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m4(\\+|$)" OR
+       CMAKE_SYSTEM_PROCESSOR MATCHES "cortex-m7(\\+|$)")
     set(FLOAT hard)
     set(FPU_CONFIG "fpv4-sp-d16")
     add_compile_options(-mfpu=${FPU_CONFIG})