parport: parport_pc: Mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 114730 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/parport/parport_pc.c

@@ -1667,7 +1667,7 @@ static int parport_ECP_supported(struct parport *pb)
 	default:
 		printk(KERN_WARNING "0x%lx: Unknown implementation ID\n",
 			pb->base);
-		/* Assume 1 */
+		/* Fall through - Assume 1 */
 	case 1:
 		pword = 1;
 	}