staging: wilc1000: remove unnecessary typecast

Remove ununecessary typecast for kzalloc.This patch was generated by
coccinelle tool

Signed-off-by: Hari Prasath Gujulan Elango <hgujulan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>