staging: rtl8192u: remove return from end of void function

This patch removes the return statement at the end of a void
function as it is not necessary.

found by checkpatch.pl: WARNING: void function return statements
are not generally useful

changes made using coccinelle script:

@@
@@

... when != if (...) return;
    when != if (...) { ... return;}
-return;

Signed-off-by: Supriya Karanth <iskaranth@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>