Asus PRIME Z370-A Windows color fix

Since the change from older versions to the 0.6, where all LEDs are not written in a loop anymore, but in a block, on Windows the last few LEDs don't show correct colors. Reading what is actually written revealed that incorrect bytes were written when writing more than 9 bytes at once.

So in this fix I just write the LEDs in batches of 3 (9 bytes in each write operation), this way everything's smooth and nice.