staging: rtl8723bs: core: Remove typecast in call to kfree

Remove typecast in the call to kfree as it is not needed.
Issue found using the below coccinelle script with options -I and
--recursive-includes,

@@
type t1;
expression *e;
@@

-kfree((t1 *)e);
+kfree(e);

Signed-off-by: Nachammai Karuppiah <nachukannan@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Link: https://lore.kernel.org/r/1570565858-91737-1-git-send-email-nachukannan@gmail.com


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