staging: wlan-ng: remove unnecessary casts from prism2usb.c

usb_get_intfdata returns a void pointer. It is not necessary to
explicitly cast to the desired type and removing the casts is
consistent with most use of usb_get_intfdata.

Signed-off-by: Tim Collier <osdevtc@gmail.com>
Link: https://lore.kernel.org/r/20191025084126.9181-2-osdevtc@gmail.com


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