Converted numerous proto_tree_add_none_format() calls for bitmask/flag items to proto_tree_add_bitmask().
Correctly set the length of LBT-RM and LBT-RU header blocks.
Various other cosmetic cleanups.

Change-Id: If19bbdeb10176b8059fd4cf657719b3b9817bc6a
Reviewed-on: https://code.wireshark.org/review/4776
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>