staging: rtl8188eu: os_dep: usb_intf.c: Fix to remove null pointer checks that could never happen

Removal of null pointer checks that could never happen

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>