drm/omap: panel-dsi-cm: use DEVICE_ATTR_RO

Use DEVICE_ATTR_RO helper instead of plain DEVICE_ATTR,
which makes the code a bit shorter and easier to read.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215104657.802264-36-tomi.valkeinen@ti.com

drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c

@@ -214,7 +214,7 @@ static const struct backlight_ops dsicm_bl_ops = {
 	.update_status  = dsicm_bl_update_status,
 };
 
-static ssize_t dsicm_num_errors_show(struct device *dev,
+static ssize_t num_dsi_errors_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct panel_drv_data *ddata = dev_get_drvdata(dev);
@@ -234,7 +234,7 @@ static ssize_t dsicm_num_errors_show(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", errors);
 }
 
-static ssize_t dsicm_hw_revision_show(struct device *dev,
+static ssize_t hw_revision_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct panel_drv_data *ddata = dev_get_drvdata(dev);
@@ -254,8 +254,8 @@ static ssize_t dsicm_hw_revision_show(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%02x.%02x.%02x\n", id1, id2, id3);
 }
 
-static DEVICE_ATTR(num_dsi_errors, S_IRUGO, dsicm_num_errors_show, NULL);
-static DEVICE_ATTR(hw_revision, S_IRUGO, dsicm_hw_revision_show, NULL);
+static DEVICE_ATTR_RO(num_dsi_errors);
+static DEVICE_ATTR_RO(hw_revision);
 
 static struct attribute *dsicm_attrs[] = {
 	&dev_attr_num_dsi_errors.attr,