Correct arc_summary and dbufstat python style

arc_summary and dbufstat should have two spaces
after their last function definitions.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes #5881

cmd/arc_summary/arc_summary.py

@@ -987,5 +987,6 @@ def main():
         page(Kstat)
         div2()
 
+
 if __name__ == '__main__':
     main()

cmd/dbufstat/dbufstat.py

@@ -577,5 +577,6 @@ def main():
     if tflag:
         print_dict(types_build_dict(sys.stdin))
 
+
 if __name__ == '__main__':
     main()