paacket-llc.c: Minor changes

   - Remove unneeded '#include <epan/conversation.h>';
   - tvb_length_remaining() --> tvb_reported_length_remaining();
   - Add editor modelines.

Change-Id: I8410a1286238c0fa1ec9f6b680ab0eb2665672f9
Reviewed-on: https://code.wireshark.org/review/3621
Reviewed-by: Bill Meier <wmeier@newsguy.com>