USB: OHCI: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Link: https://lore.kernel.org/r/20200707195351.GA4061@embeddedor
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ohci-hcd.c

···
 			ed_free (ohci, ed);
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	default:
 		/* caller was supposed to have unlinked any requests;
 		 * that's not our job.  can't recover; must leak ed.
···
 			ed->ed_next = ohci->ed_rm_list;
 			ed->ed_prev = NULL;
 			ohci->ed_rm_list = ed;
-			/* FALLTHROUGH */
+			fallthrough;
 		case ED_UNLINK:
 			break;
 		default:

drivers/usb/host/ohci-hub.c

···
 		ohci->hc_control |= OHCI_USB_RESET;
 		ohci_writel (ohci, ohci->hc_control, &ohci->regs->control);
 		(void) ohci_readl (ohci, &ohci->regs->control);
-		/* FALL THROUGH */
+		fallthrough;
 	case OHCI_USB_RESET:
 		status = -EBUSY;
 		ohci_dbg (ohci, "needs reinit!\n");

drivers/usb/host/ohci-q.c

···
 		/* ... and periodic urbs have extra accounting */
 		periodic = ohci_to_hcd(ohci)->self.bandwidth_int_reqs++ == 0
 			&& ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0;
-		/* FALLTHROUGH */
+		fallthrough;
 	case PIPE_BULK:
 		info = is_out
 			? TD_T_TOGGLE | TD_CC | TD_DP_OUT
···
 	case TD_DATAUNDERRUN:
 		if ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0)
 			break;
-		/* fallthrough */
+		fallthrough;
 	case TD_CC_STALL:
 		if (usb_pipecontrol (urb->pipe))
 			break;
-		/* fallthrough */
+		fallthrough;
 	default:
 		ohci_dbg (ohci,
 			"urb %p path %s ep%d%s %08x cc %d --> status %d\n",

drivers/usb/host/ohci-tmio.c

···
 	switch (ohci->num_ports) {
 		default:
 			dev_err(&dev->dev, "Unsupported amount of ports: %d\n", ohci->num_ports);
-			/* fall through */
+			fallthrough;
 		case 3:
 			pm |= CCR_PM_USBPW3;
-			/* fall through */
+			fallthrough;
 		case 2:
 			pm |= CCR_PM_USBPW2;
-			/* fall through */
+			fallthrough;
 		case 1:
 			pm |= CCR_PM_USBPW1;
 	}