packet-q931.c: Reformat hf[] entries; Convert apparent "4-space tabs" to spaces. Adjust editor modelines.

Change-Id: Iaeb321f0facfc6b3176677779e6cdf5c92226dec
Reviewed-on: https://code.wireshark.org/review/4496
Reviewed-by: Bill Meier <wmeier@newsguy.com>