leds: enable support for blink_set() platform hook in leds-gpio

Enhance leds-gpio to provide hardware-based led flashing by passing
through the blink_set() call to a optionally set platform-specific
function pointer.

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b07e3d4..c195a67 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -126,6 +126,9 @@
 struct gpio_led_platform_data {
 	int 		num_leds;
 	struct gpio_led *leds;
+	int		(*gpio_blink_set)(unsigned gpio,
+					unsigned long *delay_on,
+					unsigned long *delay_off);
 };