usb: ch9: make usb_endpoint_maxp() return only packet size

Now that we have a helper to gather periodic
endpoints' multiplier bits from wMaxPacketSize and
every driver is using it, we can safely make sure
that usb_endpoint_maxp() returns only bits 10:0 of
wMaxPacketSize which is where the actual packet size
lies.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

include/uapi/linux/usb/ch9.h

@@ -423,6 +423,7 @@ struct usb_endpoint_descriptor {
 #define USB_ENDPOINT_XFER_INT		3
 #define USB_ENDPOINT_MAX_ADJUSTABLE	0x80
 
+#define USB_ENDPOINT_MAXP_MASK	0x07ff
 #define USB_EP_MAXP_MULT_SHIFT	11
 #define USB_EP_MAXP_MULT_MASK	(3 << USB_EP_MAXP_MULT_SHIFT)
 #define USB_EP_MAXP_MULT(m) \
@@ -628,11 +629,11 @@ static inline int usb_endpoint_is_isoc_out(
  * usb_endpoint_maxp - get endpoint's max packet size
  * @epd: endpoint to be checked
  *
- * Returns @epd's max packet
+ * Returns @epd's max packet bits [10:0]
  */
 static inline int usb_endpoint_maxp(const struct usb_endpoint_descriptor *epd)
 {
-	return __le16_to_cpu(epd->wMaxPacketSize);
+	return __le16_to_cpu(epd->wMaxPacketSize) & USB_ENDPOINT_MAXP_MASK;
 }
 
 /**