staging: wilc1000: use memdup_user

This patch replaces the kmalloc followed by copy_from_user by the
wrapper routine memdup_user.

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