Build: Give a higher priority to the platform configuration.

- Give a higher priority to the platform configuration.
- Delete #undef from platform configurations.
- Allow tuning of profile configurations by platforms or projects.

Signed-off-by: Andrej Butok <andrey.butok@nxp.com>
Change-Id: I2e59f48bc9eece77279351b93794c6802a73a811
diff --git a/docs/configuration/header_file_system.rst b/docs/configuration/header_file_system.rst
index 06c9982..88ccdb6 100644
--- a/docs/configuration/header_file_system.rst
+++ b/docs/configuration/header_file_system.rst
@@ -39,14 +39,14 @@
 
 .. code-block:: c
 
-    #ifdef PROJECT_CONFIG_HEADER_FILE
-    #include PROJECT_CONFIG_HEADER_FILE
-    #endif
-
     #ifdef TARGET_CONFIG_HEADER_FILE
     #include TARGET_CONFIG_HEADER_FILE
     #endif
 
+    #ifdef PROJECT_CONFIG_HEADER_FILE
+    #include PROJECT_CONFIG_HEADER_FILE
+    #endif
+
     #include "config_base.h"
 
 Each component can implement a ``config_<comp_name>_check.h`` to validate component specific config