staging:wlan-ng: remove all the return statements at the end of functions

this file is having all unnecessary return statements at the end of functions
which return void, remove all of them.

some of the functions still uses the return for having the goto end,
which the label end defined at the end of the function which returns
void, this will be cleaned up in next change

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>