monitor/hmp: print trace as option in help for log command

monitor/hmp: print trace as option in help for log command

The below is printed when printing help information in qemu-system-x86_64
command line, and when CONFIG_TRACE_LOG is enabled:

----------------------------
$ qemu-system-x86_64 -d help
... ...
trace:PATTERN   enable trace events

Use "-d trace:help" to get a list of trace events.
----------------------------

However, the options of "trace:PATTERN" are only printed by
"qemu-system-x86_64 -d help", but missing in hmp "help log" command.

Fixes: c84ea00dc2 ("log: add "-d trace:PATTERN"")
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20220831213943.8155-1-dongli.zhang@oracle.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>