Convert comment from ISO-8859-1 encoding to UTF-8 to match the rest
of QEMU's source code.

Reviewed-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>