drivers/leds/leds-lp5521.c: add 'update_config' in the lp5521_platform_data

drivers/leds/leds-lp5521.c: add 'update_config' in the lp5521_platform_data

The value of CONFIG register(Addr 08h) is configurable.  For supporting
this feature, update_config is added in the platform data.  If
'update_config' is not defined, the default value is 'LP5521_PWRSAVE_EN |
LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT'.

To define CONFIG register in the platform data, the bit definitions were
mo= ved to the header file.

Documentation updated : description about 'update_config' and example.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Arun MURTHY <arun.murthy@stericsson.com>
Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>