staging: r8188eu: remove an obsolete comment

The function that this comment describes is not present in the
r8188eu driver. The comment can be removed.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211005200821.19783-1-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>