数据手册上有这样一段话：
A particular feature of the LP55231 is the ratiometric up/down dimming of the RGB-LEDs. In other words, the
LED driver PWM output will vary in a ratiometric manner. By a ratiometric approach the emitted color of an
RGB–LED remains the same regardless of the initial magnitudes of the R/G/B PWM outputs. For example, if
the PWM output of the red LED output is doubled, the output of green LED is doubled also.
但是如果我要 enables ratiometric diming该功能，如何使用该功能呢？貌似手册里并没有介绍。所以请教该功能使能后，要怎么使用呢？