In commit 5edab03d we added tracepoints to the ps2 keyboard
and mouse emulation. However we didn't remove all the debug-by-printf
support. In fact there is only one printf() remaining, and it is
redundant with the trace_ps2_write_mouse() event next to it.
Remove the printf() and the now-unused DEBUG* macros.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20201101133258.4240-1-peter.maydell@linaro.org