i2c: parport: fix spelling mistake: "Atmost" -> "At most"

There is a spelling mistake in a module parameter description.
Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>