ACPI: use kstrto*() instead of simple_strto*()

simple_strto*() are obsolete; use kstrto*() instead. Add proper error
checking.

Signed-off-by: Christoph Jaeger <christophjaeger@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 3f2bdc8..bad25b0 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -235,7 +235,8 @@
 static unsigned long acpi_rsdp;
 static int __init setup_acpi_rsdp(char *arg)
 {
-	acpi_rsdp = simple_strtoul(arg, NULL, 16);
+	if (kstrtoul(arg, 16, &acpi_rsdp))
+		return -EINVAL;
 	return 0;
 }
 early_param("acpi_rsdp", setup_acpi_rsdp);