tty: hvc: fix return value of __setup handler

__setup() handlers should return 1 to indicate that the boot option
has been handled or 0 to indicate that it was not handled.
Add a pr_warn() message if the option value is invalid and then
always return 1.

Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Fixes: 86b40567 ("tty: replace strict_strtoul() with kstrtoul()")
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Julian Wiedmann <jwi@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Reported-by: NIgor Zhbanov <i.zhbanov@omprussia.ru>
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220308024228.20477-1-rdunlap@infradead.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/hvc/hvc_iucv.c

@@ -1417,7 +1417,9 @@ static int __init hvc_iucv_init(void)
  */
 static	int __init hvc_iucv_config(char *val)
 {
-	 return kstrtoul(val, 10, &hvc_iucv_devices);
+	if (kstrtoul(val, 10, &hvc_iucv_devices))
+		pr_warn("hvc_iucv= invalid parameter value '%s'\n", val);
+	return 1;
 }