visualization: fix html report generation

Fix a couple of issues with syntax that cause I/O errors during
generation of the HTML report. These cause the
tf-test-result-visualization job to fail.

Change-Id: I11e3ec717a80893b7188dfe74fd4446d567cbd48
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/script/gen_results_report.py b/script/gen_results_report.py
index 64918b2..767e720 100755
--- a/script/gen_results_report.py
+++ b/script/gen_results_report.py
@@ -66,8 +66,7 @@
     print(results_row, file=fd)
 
     # Format table button to link to full-size plot of results.
-    TABLE_FOOTER.format(build_url + "/" + png_path)
-    print(TABLE_FOOTER, file=fd)
+    print(TABLE_FOOTER.format(build_url + png_path), file=fd)
 
 
 if __name__ == "__main__":
@@ -105,7 +104,7 @@
 
     with open(output_path, "w") as fd:
         try:
-            main(output_path, csv_path, png_path)
+            main(fd, csv_path, png_path)
         except:
             print_error_message(fd)
             raise