leds: add camera LED triggers

Some LED devices support flash/torch functionality through the LED subsystem.
This patch enables direct LED trigger controls by the driver.
Flash on/off and torch on/off can be done simply by other driver space.
Two trigger APIs are added, ledtrig_flash_ctrl() and ledtrig_torch_ctrl().

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/trigger/Kconfig

@@ -100,4 +100,12 @@ config LEDS_TRIGGER_TRANSIENT
 	  GPIO/PWM based hardware.
 	  If unsure, say Y.
 
+config LEDS_TRIGGER_CAMERA
+	tristate "LED Camera Flash/Torch Trigger"
+	depends on LEDS_TRIGGERS
+	help
+	  This allows LEDs to be controlled as a camera flash/torch device.
+	  This enables direct flash/torch on/off by the driver, kernel space.
+	  If unsure, say Y.
+
 endif # LEDS_TRIGGERS