leds: multicolor: Use rounded division when calculating color components

leds: multicolor: Use rounded division when calculating color components

Given channel intensity, LED brightness and max LED brightness, the
multicolor LED framework helper led_mc_calc_color_components() computes
the color channel brightness as

    chan_brightness = brightness * chan_intensity / max_brightness

Consider the situation when (brightness, intensity, max_brightness) is
for example (16, 15, 255), then chan_brightness is computed to 0
although the fractional divison would give 0.94, which should be rounded
to 1.

Use DIV_ROUND_CLOSEST here for the division to give more realistic
component computation:

    chan_brightness = DIV_ROUND_CLOSEST(brightness * chan_intensity,
                                        max_brightness)

Fixes: 55d5d3b46b08 ("leds: multicolor: Introduce a multicolor class definition")
Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230801124931.8661-1-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>