staging: rtl8723bs: remove casts to pointers in kfree

Remove unnecessary casts in pointer types passed to kfree.

Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Link: https://lore.kernel.org/r/20191015112637.20824-1-wambui.karugax@gmail.com


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