usb: host: pci-quirks: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/pci-quirks.c

@@ -841,7 +841,7 @@ static void quirk_usb_disable_ehci(struct pci_dev *pdev)
 			ehci_bios_handoff(pdev, op_reg_base, cap, offset);
 			break;
 		case 0: /* Illegal reserved cap, set cap=0 so we exit */
-			cap = 0; /* then fallthrough... */
+			cap = 0; /* fall through */
 		default:
 			dev_warn(&pdev->dev,
 				 "EHCI: unrecognized capability %02x\n",