tracing: Add missing spaces in trace_print_hex_seq()

If the buffer length is larger than 16 and concatenate is set to false,
there would be missing spaces every 16 bytes.
Example:
  Before: c5 11 10 50 05 4d 31 40 00 40 00 40 00 4d 31 4000 40 00
  After:  c5 11 10 50 05 4d 31 40 00 40 00 40 00 4d 31 40 00 40 00

Link: https://lore.kernel.org/linux-trace-kernel/20230426032257.3157247-1-lyenting@google.com

Signed-off-by: Ken Lin <lyenting@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: lyenting

kernel/trace/trace_output.c

@@ -221,8 +221,11 @@ trace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len,
 	const char *ret = trace_seq_buffer_ptr(p);
 	const char *fmt = concatenate ? "%*phN" : "%*ph";
 
-	for (i = 0; i < buf_len; i += 16)
+	for (i = 0; i < buf_len; i += 16) {
+		if (!concatenate && i != 0)
+			trace_seq_putc(p, ' ');
 		trace_seq_printf(p, fmt, min(buf_len - i, 16), &buf[i]);
+	}
 	trace_seq_putc(p, 0);
 
 	return ret;