Kernel: Fix index calculation in NVMeQueue submit_sync_sqe function

There was a bug while calculating the next index in submit_sync_sqe
function. Use the NVMeQueue's class variable m_qdepth instead of the
hardcoded IO_QUEUE_SIZE.

Kernel/Storage/NVMe/NVMeQueue.cpp

@@ -123,7 +123,7 @@ u16 NVMeQueue::submit_sync_sqe(NVMeSubmission& sub)
             SpinlockLocker lock(m_cq_lock);
             index = m_cq_head - 1;
             if (index < 0)
-                index = IO_QUEUE_SIZE - 1;
+                index = m_qdepth - 1;
         }
         cqe_cid = m_cqe_array[index].command_id;
         Scheduler::yield();