usb: gadget: change len to size_t on alloc_ep_req()

Length of buffers should be of type size_t whenever possible. Altough
recommended, this change has no real practical change, unless a driver has a
uses a huge or negative buffer size - it might help find these bugs.
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/u_f.c

@@ -13,7 +13,7 @@
 
 #include "u_f.h"
 
-struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len)
+struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len)
 {
 	struct usb_request      *req;
 

drivers/usb/gadget/u_f.h

@@ -48,7 +48,7 @@ struct usb_ep;
 struct usb_request;
 
 /* Requests allocated via alloc_ep_req() must be freed by free_ep_req(). */
-struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len);
+struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_len);
 static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req)
 {
 	kfree(req->buf);