chan_pjsip: Changed to continued after invalid media for pjsip show channelstats

Currently, the pjsip show channelstats cli does not show channel's
stats after hits the invalid channel info. This makes hard to use
this cli. Changed to keep iterate after hits the invalid channel
info.

ASTERISK-28292

Change-Id: I3efdff1c9e1b1efd3c971fb82ae77aa133a6f43c

channels/pjsip/cli_commands.c

@@ -356,7 +356,7 @@ static int cli_channelstats_print_body(void *obj, void *arg, int flags)
 	if (!media || !media->rtp) {
 		ast_str_append(&context->output_buffer, 0, " %s not valid\n", snapshot->name);
 		ao2_cleanup(channel);
-		return -1;
+		return 0;
 	}
 
 	codec_in_use[0] = '\0';