leds-lm3530: fixes for aries

Change-Id: I6f70ee9d2351b1ea93962851e97a5ebfc54328ce
apq8064: register lm3530 backlight device

Change-Id: I4da8be05d4a5c3ed9677a0ecfc72ca2762657f79
leds-lm3530: add exported function for setting brightness

Change-Id: I18aa739b11050537791e74387ef89d8856927d80