staging: mt7621-gpio: add kerneldoc for state data containers

This commit adds kerneldoc for the two data containers in
order to better understanding of its existence.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-gpio/gpio-mt7621.c

@@ -31,6 +31,14 @@
 #define GPIO_REG_STAT	0x90
 #define GPIO_REG_EDGE	0xA0
 
+/**
+ * struct mtk_gc - data for a single gpio-chip
+ * @chip: gpio chip instance
+ * @lock: spinlock to protect the chip
+ * @bank: gpio bank number for the chip
+ * @rising: mask for rising irqs
+ * @falling: mask for falling irqs
+ */
 struct mtk_gc {
 	struct gpio_chip chip;
 	spinlock_t lock;
@@ -39,6 +47,16 @@ struct mtk_gc {
 	u32 falling;
 };
 
+/**
+ * struct mtk_data - state container for
+ * data of the platform driver. It is a
+ * single irq-chip but 3 separate gpio-chip.
+ * @dev: device instance
+ * @gpio_membase: memory base address
+ * @gpio_irq: irq number from the device tree
+ * @gpio_irq_domain: irq domain for this chip
+ * @gc_map: array of the gpio chips
+ */
 struct mtk_data {
 	struct device *dev;
 	void __iomem *gpio_membase;