usb-storage: remove MSDState->residue

We have the field twice, once in MSDState directly and one in the status
word struct.  Drop one.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb/dev-storage.c

@@ -51,7 +51,6 @@ typedef struct {
     uint32_t scsi_len;
     uint8_t *scsi_buf;
     uint32_t data_len;
-    uint32_t residue;
     struct usb_msd_csw csw;
     SCSIRequest *req;
     SCSIBus bus;
@@ -229,11 +228,10 @@ static void usb_msd_command_complete(SCSIRequest *req, uint32_t status, size_t r
     USBPacket *p = s->packet;
 
     DPRINTF("Command complete %d tag 0x%x\n", status, req->tag);
-    s->residue = s->data_len;
 
     s->csw.sig = cpu_to_le32(0x53425355);
     s->csw.tag = cpu_to_le32(req->tag);
-    s->csw.residue = cpu_to_le32(s->residue);
+    s->csw.residue = cpu_to_le32(s->data_len);
     s->csw.status = status != 0;
 
     if (s->packet) {
@@ -378,7 +376,7 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             }
             DPRINTF("Command tag 0x%x flags %08x len %d data %d\n",
                     tag, cbw.flags, cbw.cmd_len, s->data_len);
-            s->residue = 0;
+            assert(le32_to_cpu(s->csw.residue) == 0);
             s->scsi_len = 0;
             s->req = scsi_req_new(s->scsi_dev, tag, 0, cbw.cmd, NULL);
             scsi_req_enqueue(s->req);
@@ -397,7 +395,7 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             if (s->scsi_len) {
                 usb_msd_copy_data(s, p);
             }
-            if (s->residue) {
+            if (le32_to_cpu(s->csw.residue)) {
                 int len = p->iov.size - p->result;
                 if (len) {
                     usb_packet_skip(p, len);
@@ -458,7 +456,7 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             if (s->scsi_len) {
                 usb_msd_copy_data(s, p);
             }
-            if (s->residue) {
+            if (le32_to_cpu(s->csw.residue)) {
                 int len = p->iov.size - p->result;
                 if (len) {
                     usb_packet_skip(p, len);