DM USB: re-implement the data block process logic

In Windows OS, there are many non-data blocks (EVENT DATA) during the USB
data transfer process, which is very different from the Linux conterpart.
To support both OS, the data processing logic is changed with the help of
newly introduced enum usb_block_type.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>

devicemodel/include/usb_pmapper.h

@@ -73,9 +73,9 @@ struct usb_dev_req {
 	 * so here need some data to record it.
 	 */
 	uint8_t	*buffer;
-	int     buf_length;
-	int     blk_start;
-	int     blk_count;
+	int     buf_size;
+	int     blk_head;
+	int     blk_tail;
 
 	struct usb_xfer *xfer;
 	struct libusb_transfer *trn;