leds-lp5523: clean up lp5523_configure()

 This patch is a preceding step for making common lp55xx init function.

 Return code:
 Do not use 'OR' arithmetic for the result.
 If some error occurs, just return it.

 Remove engine verification code:
 To check whether internal engine works or not, many lines of code are executed.
 However, this job is unnecessary during the chip initialization because
 the engine usage is not mandatory but optional function.
 LED engines are enabled when specific LED pattern is loaded.
 Therefore, this verification code is removed.

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