leds: Add driver for LT3593 controlled LEDs

The LT3593 is a step-up DC/DC converter designed to drive up to ten
white LEDs in series. The current flow can be set with a control pin.

This driver controls any number of such devices connected on generic
GPIOs and exports the function as as platform_driver.

The gpio_led platform data struct definition is reused for this purpose.

Successfully tested on a PXA embedded board.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 12b7a20..eb5a141 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -30,6 +30,7 @@
 obj-$(CONFIG_LEDS_WM8350)		+= leds-wm8350.o
 obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
 obj-$(CONFIG_LEDS_INTEL_SS4200)		+= leds-ss4200.o
+obj-$(CONFIG_LEDS_LT3593)		+= leds-lt3593.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o