ARM: shmobile: koelsch: set .debounce_interval

In R-Car GPIO hardware block, 'chattering removal' feature can be
enabled on GPIO-n-[3:0] pins, but it's not supported on rest of pins
GPIO-n-[31:4].

Set an appropriate debounce interval, instead.  We could confirm that
spurious/unnecessary GPIO interrupts are prevented by this settings.

Based on work for the lager board by Shinya Kuribayashi.

Cc: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/mach-shmobile/board-koelsch.c

@@ -56,7 +56,8 @@ static const struct gpio_led_platform_data koelsch_leds_pdata __initconst = {
 
 /* GPIO KEY */
 #define GPIO_KEY(c, g, d, ...) \
-	{ .code = c, .gpio = g, .desc = d, .active_low = 1 }
+	{ .code = c, .gpio = g, .desc = d, .active_low = 1, \
+	  .debounce_interval = 20 }
 
 static struct gpio_keys_button gpio_buttons[] = {
 	GPIO_KEY(KEY_4,		RCAR_GP_PIN(5, 3),	"SW2-pin4"),