[FOR-UPSTREAM] hid-asus-ally: mcu_version attribute

Add the mcu_version sysfs attribute so that userspace has a way to check
the MCU FW version.

Signed-off-by: Luke Jones <luke@ljones.dev>

Author: flukejones

drivers/hid/hid-asus-ally.c

@@ -377,6 +377,7 @@ static struct ally_drvdata {
 	struct ally_gamepad_cfg *gamepad_cfg;
 	struct ally_rgb_dev *led_rgb_dev;
 	struct ally_rgb_data led_rgb_data;
+	uint mcu_version;
 } drvdata;
 
 /**
@@ -1192,13 +1193,21 @@ static ssize_t gamepad_mode_store(struct device *dev, struct device_attribute *a
 
 DEVICE_ATTR_RW(gamepad_mode);
 
+static ssize_t mcu_version_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", drvdata.mcu_version);
+}
+
+DEVICE_ATTR_RO(mcu_version);
+
 /* ROOT LEVEL ATTRS *******************************************************************************/
 static struct attribute *gamepad_device_attrs[] = {
 	&dev_attr_btn_mapping_reset.attr,
 	&dev_attr_gamepad_mode.attr,
 	&dev_attr_gamepad_apply_all.attr,
 	&dev_attr_gamepad_vibration_intensity.attr,
 	&dev_attr_gamepad_vibration_intensity_index.attr,
+	&dev_attr_mcu_version.attr,
 	NULL
 };