Initialize the isochronous lock earlier.

The constructor may abort at various places and the destructor cleans up
everything already initialized. The mutex was however not initialized
early on, leading to #8153 where the mutex was destroied in the error
case, accessing uninitialized memory. Fixes #8153 though the reason for
the aborted constructor probably needs to be investigated as well.

src/add-ons/kernel/busses/usb/uhci.cpp

@@ -399,6 +399,9 @@ UHCI::UHCI(pci_info *info, Stack *stack)
 		fRootHubAddress(0),
 		fPortResetChange(0)
 {
+	// Create a lock for the isochronous transfer list
+	mutex_init(&fIsochronousLock, "UHCI isochronous lock");
+
 	if (!fInitOK) {
 		TRACE_ERROR("bus manager failed to init\n");
 		return;
@@ -533,9 +536,6 @@ UHCI::UHCI(pci_info *info, Stack *stack)
 		"uhci cleanup thread", B_NORMAL_PRIORITY, (void *)this);
 	resume_thread(fCleanupThread);
 
-	// Create a lock for the isochronous transfer list
-	mutex_init(&fIsochronousLock, "UHCI isochronous lock");
-
 	// Create semaphore the isochronous finisher thread will wait for
 	fFinishIsochronousTransfersSem = create_sem(0,
 		"UHCI Isochronous Finish Transfers");