USB: Add usb_endpoint_xfer_control to usb.h

Added a function to check if an endpoint is a control endpoint.
There were similar functions for bulk, interrupt, and isoc,
but not for control endpoints.

Signed-off-by: Sarah Bailey <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

include/linux/usb.h

···
 }
 
 /**
+ * usb_endpoint_xfer_control - check if the endpoint has control transfer type
+ * @epd: endpoint to be checked
+ *
+ * Returns true if the endpoint is of type control, otherwise it returns false.
+ */
+static inline int usb_endpoint_xfer_control(const struct usb_endpoint_descriptor *epd)
+{
+	return ((epd->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+		USB_ENDPOINT_XFER_CONTROL);
+}
+
+/**
  * usb_endpoint_xfer_int - check if the endpoint has interrupt transfer type
  * @epd: endpoint to be checked
  *