usb: dwc3: gadget: fix DMA offset calculation

Fix offset calculation in dwc3_trb_dma_offset()

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 16f2ba6..ee5c1a5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -189,7 +189,7 @@
 static dma_addr_t dwc3_trb_dma_offset(struct dwc3_ep *dep,
 		struct dwc3_trb_hw *trb)
 {
-	u32		offset = trb - dep->trb_pool;
+	u32		offset = (char *) trb - (char *) dep->trb_pool;
 
 	return dep->trb_pool_dma + offset;
 }