drm/panel: dsi-cm: replace snprintf in show functions with sysfs_emit

show() must not use snprintf() when formatting the value to be
returned to user space.

Fix the following coccicheck warning:
drivers/gpu/drm/panel/panel-dsi-cm.c:251: WARNING: use scnprintf or sprintf.
drivers/gpu/drm/panel/panel-dsi-cm.c:271: WARNING: use scnprintf or sprintf.

Use sysfs_emit instead of scnprintf or sprintf makes more sense.
Signed-off-by: Qing Wang <wangqing@vivo.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1634280490-4429-1-git-send-email-wangqing@vivo.com

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

@@ -248,7 +248,7 @@ static ssize_t num_dsi_errors_show(struct device *dev,
 	if (r)
 		return r;
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", errors);
+	return sysfs_emit(buf, "%d\n", errors);
 }
 
 static ssize_t hw_revision_show(struct device *dev,
@@ -268,7 +268,7 @@ static ssize_t hw_revision_show(struct device *dev,
 	if (r)
 		return r;
 
-	return snprintf(buf, PAGE_SIZE, "%02x.%02x.%02x\n", id1, id2, id3);
+	return sysfs_emit(buf, "%02x.%02x.%02x\n", id1, id2, id3);
 }
 
 static DEVICE_ATTR_RO(num_dsi_errors);