udmabuf: drop WARN_ON() check.

Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20180911134216.9760-12-kraxel@redhat.com

drivers/dma-buf/udmabuf.c

@@ -25,9 +25,6 @@ static int udmabuf_vm_fault(struct vm_fault *vmf)
 	struct vm_area_struct *vma = vmf->vma;
 	struct udmabuf *ubuf = vma->vm_private_data;
 
-	if (WARN_ON(vmf->pgoff >= ubuf->pagecount))
-		return VM_FAULT_SIGBUS;
-
 	vmf->page = ubuf->pages[vmf->pgoff];
 	get_page(vmf->page);
 	return 0;