Rename DEV_MODE to GEN_FILES

GEN_FILES is a bit clearer as it describes what the setting
does more precisely.

Signed-off-by: David Horstmann <david.horstmann@arm.com>

programs/psa/CMakeLists.txt

@@ -4,7 +4,7 @@ set(executables
     psa_constant_names
 )
 
-if(DEV_MODE)
+if(GEN_FILES)
     add_custom_command(
         OUTPUT
             ${CMAKE_CURRENT_BINARY_DIR}/psa_constant_names_generated.c
@@ -30,7 +30,7 @@ foreach(exe IN LISTS executables)
 endforeach()
 
 target_include_directories(psa_constant_names PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
-if(DEV_MODE)
+if(GEN_FILES)
     add_custom_target(generate_psa_constant_names_generated_c
         DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/psa_constant_names_generated.c)
     add_dependencies(psa_constant_names generate_psa_constant_names_generated_c)

programs/ssl/CMakeLists.txt

@@ -18,7 +18,7 @@ set(executables
     ssl_server2
 )
 
-if(DEV_MODE)
+if(GEN_FILES)
     # Inform CMake that the following file will be generated as part of the build
     # process, so it doesn't complain that it doesn't exist yet. Starting from
     # CMake 3.20, this will no longer be necessary as CMake will automatically
@@ -42,7 +42,7 @@ foreach(exe IN LISTS executables)
     target_link_libraries(${exe} ${libs})
     target_include_directories(${exe} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../../tests/include)
     if(exe STREQUAL "ssl_client2" OR exe STREQUAL "ssl_server2")
-        if(DEV_MODE)
+        if(GEN_FILES)
             add_dependencies(${exe} generate_query_config_c)
         endif()
         target_include_directories(${exe}

programs/test/CMakeLists.txt

@@ -27,7 +27,7 @@ if(TEST_CPP)
     target_link_libraries(cpp_dummy_build ${mbedcrypto_target})
 endif()
 
-if(DEV_MODE)
+if(GEN_FILES)
     find_package(Perl REQUIRED)
 
     add_custom_command(