staging: mt7621-gpio: change lock place in irq mask and unmask functions

Functions mediatek_gpio_irq_umask mediatek_gpio_irq_unmask are
reading and modifying registers but only the write is being hold.
It should be a complete lock instead for those which are type of
"read-modify-write". This makes more sense.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -231,10 +231,9 @@ mediatek_gpio_irq_unmask(struct irq_data *d)
 	if (!rg)
 		return;
 
+	spin_lock_irqsave(&rg->lock, flags);
 	rise = mtk_gpio_r32(rg, GPIO_REG_REDGE);
 	fall = mtk_gpio_r32(rg, GPIO_REG_FEDGE);
-
-	spin_lock_irqsave(&rg->lock, flags);
 	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise | (PIN_MASK(pin) & rg->rising));
 	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall | (PIN_MASK(pin) & rg->falling));
 	spin_unlock_irqrestore(&rg->lock, flags);
@@ -253,10 +252,9 @@ mediatek_gpio_irq_mask(struct irq_data *d)
 	if (!rg)
 		return;
 
+	spin_lock_irqsave(&rg->lock, flags);
 	rise = mtk_gpio_r32(rg, GPIO_REG_REDGE);
 	fall = mtk_gpio_r32(rg, GPIO_REG_FEDGE);
-
-	spin_lock_irqsave(&rg->lock, flags);
 	mtk_gpio_w32(rg, GPIO_REG_FEDGE, fall & ~PIN_MASK(pin));
 	mtk_gpio_w32(rg, GPIO_REG_REDGE, rise & ~PIN_MASK(pin));
 	spin_unlock_irqrestore(&rg->lock, flags);