"Asian" is a broad term. "European" could describe a lot of very different people, it's the same thing with "Asian". Are you Chinese, Japanese, Korean, Filipino, Vietnamese, Indonesian... I mean, some of them are likely to have dark brown penises, and some of them are not.
At the end of the day, it doesn't really matter. You've got what you got. Truth is, I doubt most women care what color your genitals are. They could be fluorescent orange. Nobody is ever attracted to anyone because of the color of their rude bits.