driver core: Use kstrtobool() instead of strtobool()

strtobool() is the same as kstrtobool().
However, the latter is more used within the kernel.

In order to remove strtobool() and slightly simplify kstrtox.h, switch to
the other function name.

While at it, include the corresponding header file (<linux/kstrtox.h>)
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/02ba683a5c0716638ad8ca11e8b0fdca97c4f294.1667336095.git.christophe.jaillet@wanadoo.frSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/fwnode.h>
 #include <linux/init.h>
+#include <linux/kstrtox.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -1628,7 +1629,7 @@ early_param("fw_devlink", fw_devlink_setup);
 static bool fw_devlink_strict;
 static int __init fw_devlink_strict_setup(char *arg)
 {
-	return strtobool(arg, &fw_devlink_strict);
+	return kstrtobool(arg, &fw_devlink_strict);
 }
 early_param("fw_devlink.strict", fw_devlink_strict_setup);
 
@@ -2280,7 +2281,7 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
 {
 	struct dev_ext_attribute *ea = to_ext_attr(attr);
 
-	if (strtobool(buf, ea->var) < 0)
+	if (kstrtobool(buf, ea->var) < 0)
 		return -EINVAL;
 
 	return size;
@@ -2534,7 +2535,7 @@ static ssize_t online_store(struct device *dev, struct device_attribute *attr,
 	bool val;
 	int ret;
 
-	ret = strtobool(buf, &val);
+	ret = kstrtobool(buf, &val);
 	if (ret < 0)
 		return ret;