staging: wilc1000: Modification in code to use ARRAY_SIZE macro

In this patch, ARRAY_SIZE() macro is used to determine the
size. This change was detected with the help of coccinelle
tool.

Signed-off-by: Chaitanya Dhere <cvijaydh@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>