pibridge-serdev: add comments for tracing macros
requested to merge github/fork/linosanfilippo-kunbus/revpi-2860/add_tracing_comments into devel/revpi-5.10-serdev
Created by: linosanfilippo-kunbus
Add comments to the tracing macros that describe which information each event provides and when the event is triggered.
Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com