staging: vt6656: int.c: Remove unneeded cast

When assigning a void* to a variable <of some other type>, the value
is cast implicitly - there's no need for explicit cast.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>