perf: script: fix missing ',' for fields option

A comma is missed at the end of line.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
Link: https://lore.kernel.org/r/20231017015524.797065-1-changbin.du@huawei.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: Changbin Du

tools/perf/builtin-script.c

@@ -3899,7 +3899,7 @@ int cmd_script(int argc, const char **argv)
 		     "comma separated output fields prepend with 'type:'. "
 		     "+field to add and -field to remove."
 		     "Valid types: hw,sw,trace,raw,synth. "
-		     "Fields: comm,tid,pid,time,cpu,event,trace,ip,sym,dso,dsoff"
+		     "Fields: comm,tid,pid,time,cpu,event,trace,ip,sym,dso,dsoff,"
 		     "addr,symoff,srcline,period,iregs,uregs,brstack,"
 		     "brstacksym,flags,data_src,weight,bpf-output,brstackinsn,"
 		     "brstackinsnlen,brstackoff,callindent,insn,insnlen,synth,"