The delete_flow__() function had two callers, each of which had to
correctly call ofmonitor_flush() when completely done. An upcoming commit
will add another function that the callers need to call. This is easier
if delete_flow__() only has one caller, so this commit refactors so that
it does, and inlines delete_flow__() into that caller for further
simplification.
Also remove a parameter from delete_flows__() that wasn't really needed
and change its return type to void since it can't ever fail.
Signed-off-by: Ben Pfaff <blp@nicira.com> Acked-by: Thomas Graf <tgraf@suug.ch> Acked-by: Ethan Jackson <ethan@nicira.com>