ldgen: use user input filename for processed template

Previously ldgen determines the output file name on its own. This commit
makes it so that user can dictate what the output file name will be
for the processed template, if the user needs it for something else.

tools/ldgen/ldgen.py

@@ -19,6 +19,8 @@ import argparse
 import sys
 import tempfile
 import subprocess
+import os
+import errno
 
 from fragments import FragmentFile
 from sdkconfig import SDKConfig
@@ -111,6 +113,14 @@ def main():
         with tempfile.TemporaryFile("w+") as output:
             script_model.write(output)
             output.seek(0)
+
+            if not os.path.exists(os.path.dirname(output_path)):
+                try:
+                    os.makedirs(os.path.dirname(output_path))
+                except OSError as exc:
+                    if exc.errno != errno.EEXIST:
+                        raise
+
             with open(output_path, "w") as f:  # only create output file after generation has suceeded
                 f.write(output.read())
     except LdGenFailure as e: