Fix lerp16by16 where uint32_t should be uint16_t
Fix lerp16by16 where uint32_t should be uint16_t

scale16 returns a uint16_t and it doesn't seem necessary to upcast.
FastLED/FastLED,PaulStoffregen/FastLED,PaulStoffregen/FastLED,FastLED/FastLED,PaulStoffregen/FastLED,FastLED/FastLED,FastLED/FastLED