usb: gadget: s3c-hsotg: add flush TX FIFO when kill all requests

This patch adds flushing TX FIFO in kill_all_requests() function in
dedicated-fifo mode. It's because when requests are killed (when endpoint is
disabled or in case of device reset/disconnection) in FIFO can stay some
unsent data. In the worst case FIFO can stay full, and then if endpoint will
be back enabled, sending new data will be impossible.

Signed-off-by: Robert Baldyga <[e-mail]>
Signed-off-by: Kyungmin Park <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/s3c-hsotg.c

···
 		s3c_hsotg_complete_request(hsotg, ep, req,
 					   result);
 	}
+	if(hsotg->dedicated_fifos)
+		if ((readl(hsotg->regs + DTXFSTS(ep->index)) & 0xffff) * 4 < 3072)
+			s3c_hsotg_txfifo_flush(hsotg, ep->index);
 }
 
 #define call_gadget(_hs, _entry) \