staging: rtl8188eu: os_dep: Removed unnecessary return.

This patch fixes
WARNING:  void function return statements are not generally useful
checkpatch.pl warning in usb_intf.c by using this coccinelle script

@r@
identifier i;
@@
void i(...)
{
...
-return;
}

Signed-off-by: Gulsah Kose <gulsah.1004@gmail.com>
Reviewed-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>