clang-tidy: rename mako file extesnsion

Renamed mako.cpp to cpp.mako to prevent clang-tidy from running
checks on this file. Also updated build scripts to accommodate
the new file extension.

Change-Id: I2ad35ec653cb3ebf684ddd0ba697a966fe7ed540
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/scripts/fru_gen.py b/scripts/fru_gen.py
index c79cb64..fd0941c 100755
--- a/scripts/fru_gen.py
+++ b/scripts/fru_gen.py
@@ -16,7 +16,7 @@
 
         # Render the mako template
 
-        t = Template(filename=os.path.join(script_dir, "readfru.mako.cpp"))
+        t = Template(filename=os.path.join(script_dir, "readfru.cpp.mako"))
 
         output_hpp = os.path.join(output_dir, "fru-read-gen.cpp")
         with open(output_hpp, "w") as fd: