packet-assa_r3.c: Use editor modelines from http://www.wireshark.org/tools/modelines.html

Change-Id: I2d9accd2336448ced30dca1878a3e27cdba29566
Reviewed-on: https://code.wireshark.org/review/4687
Reviewed-by: Bill Meier <wmeier@newsguy.com>