Build Helper: Extract config maps to a new file

Put all config maps for build helper into a new file.
To make the code easier to maintain.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I7e586459999707d57273caa0bece5be7fbc7b500
diff --git a/build_helper/build_helper_configs.py b/build_helper/build_helper_configs.py
index bbdebb9..236a3dc 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -373,8 +373,8 @@
                 "common_params": _common_tfm_builder_cfg,
                 "valid": [
                     # Profile Small also supports SFN model
-                    ("*", "*", False, "*", "*", "*", "*", "*", "*", "*",
-                     "*", "SFN_ENABLE")
+                    ("*", "*", False, "*", "*", "*", "*",
+                     "*", "*", "*", "*", "SFN")
                 ],
                 "invalid": _common_tfm_invalid_configs + [
                     ("arm/mps2/an519", "GCC_7_3_1", "*", "*", "*",