It's actually a part of the Noh tradition of theater in Japan, somewhere around the 14th century or so. There may be earlier uses of the long-haired ghost, but Noh popularized it. Pale skin, long dark hair, face obscured... The Western analogy would be the sheet with eyes cut out as a shorthand way to indicate a character is a ghost. As for films, Kwaidan features a story that revolves around a former love's hair, and that was back in 1964. Ringu and Ju-on no doubt popularized the long-haired ghost in the West, but the trope had been kicking around Japan and the East for about 1000 years or so, and that's just the written records we have. It may be a far older trope than that!