file: fix typo in take_fd() comment

The explanatory comment above take_fd() contains a typo, fix that to not
confuse readers.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20240809135035.748109-1-minipli@grsecurity.net


Signed-off-by: Christian Brauner <brauner@kernel.org>