misc: c2port: use kobj_to_dev()

Use kobj_to_dev() instead of open-coding it.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/c2port/core.c

@@ -721,9 +721,7 @@ static ssize_t c2port_read_flash_data(struct file *filp, struct kobject *kobj,
 				struct bin_attribute *attr,
 				char *buffer, loff_t offset, size_t count)
 {
-	struct c2port_device *c2dev =
-			dev_get_drvdata(container_of(kobj,
-						struct device, kobj));
+	struct c2port_device *c2dev = dev_get_drvdata(kobj_to_dev(kobj));
 	ssize_t ret;
 
 	/* Check the device and flash access status */
@@ -838,9 +836,7 @@ static ssize_t c2port_write_flash_data(struct file *filp, struct kobject *kobj,
 				struct bin_attribute *attr,
 				char *buffer, loff_t offset, size_t count)
 {
-	struct c2port_device *c2dev =
-			dev_get_drvdata(container_of(kobj,
-						struct device, kobj));
+	struct c2port_device *c2dev = dev_get_drvdata(kobj_to_dev(kobj));
 	int ret;
 
 	/* Check the device access status */