cppcheck report:
hw/ac97.c:1004: style:
 Variable 'written' is assigned a value that is never used
hw/ac97.c:1072: style:
 Variable 'written' is assigned a value that is never used

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>