hw/audio/es1370: Clean up comment

Replace a sweary comment with one that's a bit more helpful to
future readers of the code.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Volker Rümelin <vr_qemu@t-online.de>
Message-ID: <20231110164318.2197569-1-peter.maydell@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>