staging: r8188eu: convert SetHalDefVar8188EUsb() to void

The return value of SetHalDefVar8188EUsb() is not used. Convert the
function to void.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220128115445.6606-6-straube.linux@gmail.com


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