media: dvb-usb: remove unnecessary (void*) conversions

Pointer variables of void * type do not require type cast.

Link: https://lore.kernel.org/linux-media/20230320064039.5670-1-yuzhe@nfschina.com


Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>