Fix bridge reconnect

In the mux_epoll__add_in function, no context->events was set. Previously this was set to match the ev.events (EPOLLIN). Adding this back in, keeps the code consistent to before it was refactored to split out epoll and poll functions, as well as being consistent with the other mux_epoll__ functions.

If this is not set, the connection is never fully established when the broker comes back up.

Fixes #1680.

Signed-off-by: Simon Tate <simon.tate@bt.com>