staging: wilc1000: fix build warning related to time_after_eq macro

This patch fixes a build warning related to the use of the time_after_eq
macro.Adding a typecast to the second argument suppresses the
warning.This warning was created by one my previous patch.

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