Asterix: fix Coverity scan (1025624 & 1025625: Missing break in switch)


Two comments are added to the code to notify Coverity scan that breaks are not put in switch statement intentionally.

Change-Id: Ie391790ee7365da56ddf0bf7b19042c9a11efddd
Reviewed-on: https://code.wireshark.org/review/5554
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>