leds: lm3601x: Introduce the lm3601x LED driver

Introduce the family of LED devices that can
drive a torch, strobe or IR LED.

The LED driver can be configured with a strobe
timer to execute a strobe flash.  The IR LED
brightness is controlled via the torch brightness
register.

The data sheet for each the LM36010 and LM36011
LED drivers can be found here:
http://www.ti.com/product/LM36010
http://www.ti.com/product/LM36011



Signed-off-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>