Fix typo in the include directory for the the GCC_ARM_CM55_TFM port (#764)

Should be CM55 not CM85.
diff --git a/portable/CMakeLists.txt b/portable/CMakeLists.txt
index 988be15..a13e088 100644
--- a/portable/CMakeLists.txt
+++ b/portable/CMakeLists.txt
@@ -774,7 +774,7 @@
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM55_NONSECURE>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM55/non_secure>
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM55_SECURE>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM55/secure>
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM55_NTZ_NONSECURE>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM55_NTZ/non_secure>
-    $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM55_TFM>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM85_NTZ/non_secure>
+    $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM55_TFM>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM55_NTZ/non_secure>
 
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM85_NONSECURE>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM85/non_secure>
     $<$<STREQUAL:${FREERTOS_PORT},GCC_ARM_CM85_SECURE>:${CMAKE_CURRENT_LIST_DIR}/GCC/ARM_CM85/secure>