It's very familiar in South
Africa, but I don't see it often used elsewhere.
The heroine of an iconic 19th century SA novel by
Olive Schreiner, Story of an African Farm, is named Lyndall after the birth surname of the author's mother. Perhaps for this reason it's always been used here though never what you'd call popular.
My guess at the meaning is 'linden valley', but I'd like proof!