media: exynos4-is: use DEVICE_ATTR_RW() helper macro

Use DEVICE_ATTR_RW() helper macro instead of DEVICE_ATTR(), which is
simpler and more readable.

Due to the names of the read and write functions of the sysfs attribute is
normalized, there is a natural association.

Signed-off-by: Zhen Lei <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/exynos4-is/media-dev.c

···
 	.link_notify = fimc_md_link_notify,
 };
 
-static ssize_t fimc_md_sysfs_show(struct device *dev,
-				  struct device_attribute *attr, char *buf)
+static ssize_t subdev_conf_mode_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
 {
 	struct fimc_md *fmd = dev_get_drvdata(dev);
 
···
 	return strscpy(buf, "V4L2 video node only API (vid-dev)\n", PAGE_SIZE);
 }
 
-static ssize_t fimc_md_sysfs_store(struct device *dev,
-				   struct device_attribute *attr,
-				   const char *buf, size_t count)
+static ssize_t subdev_conf_mode_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
 {
 	struct fimc_md *fmd = dev_get_drvdata(dev);
 	bool subdev_api;
···
  *  sub-dev - for media controller API, subdevs must be configured in user
  *  space before starting streaming.
  */
-static DEVICE_ATTR(subdev_conf_mode, S_IWUSR | S_IRUGO,
-		   fimc_md_sysfs_show, fimc_md_sysfs_store);
+static DEVICE_ATTR_RW(subdev_conf_mode);
 
 static int cam_clk_prepare(struct clk_hw *hw)
 {