input: use hex in ps2 keycode trace events

Hardware scancodes are all documented in hex, so use that in trace
events to make it easier to understand.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20171019142848.572-2-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/input/trace-events

@@ -1,7 +1,7 @@
 # See docs/devel/tracing.txt for syntax documentation.
 
 # hw/input/ps2.c
-ps2_put_keycode(void *opaque, int keycode) "%p keycode %d"
+ps2_put_keycode(void *opaque, int keycode) "%p keycode 0x%02x"
 ps2_read_data(void *opaque) "%p"
 ps2_set_ledstate(void *s, int ledstate) "%p ledstate %d"
 ps2_reset_keyboard(void *s) "%p"