USB: musb: fix compiling warning with min() macro

Current musb gadget dma code produces the warning:
drivers/usb/musb/musb_gadget.c: In function 'txstate':
drivers/usb/musb/musb_gadget.c:312: warning: comparison of distinct
                                             pointer types lacks a cast

So switch to min_t(size_t, ...).

Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/musb_gadget.c

@@ -309,7 +309,7 @@ static void txstate(struct musb *musb, struct musb_request *req)
 			size_t request_size;
 
 			/* setup DMA, then program endpoint CSR */
-			request_size = min(request->length,
+			request_size = min_t(size_t, request->length,
 						musb_ep->dma->max_len);
 			if (request_size < musb_ep->packet_sz)
 				musb_ep->dma->desired_mode = 0;