usb.c: fix compiler warning USBConfigurationDescriptor
diff --git a/sam3s_example/simtrace/usb.c b/sam3s_example/simtrace/usb.c
index 1c3b664..460f316 100644
--- a/sam3s_example/simtrace/usb.c
+++ b/sam3s_example/simtrace/usb.c
@@ -587,7 +587,7 @@
/* AT91SAM3S does only support full speed, but not high speed USB */
const USBDDriverDescriptors driverDescriptors = {
&deviceDescriptor,
- (USBConfigurationDescriptor **) &(configurationDescriptorsArr), /* first full-speed configuration descriptor */
+ (const USBConfigurationDescriptor **) &(configurationDescriptorsArr), /* first full-speed configuration descriptor */
0, /* No full-speed device qualifier descriptor */
0, /* No full-speed other speed configuration */
0, /* No high-speed device descriptor */