staging: wilc1000: fixes potential null dereference 'wid.val'

This patch fixes the error reported by smatch.
 - Handle_ListenStateExpired() error: potential null dereference 'wid.val'
If kmalloc failed, referenced to a NULL pointer.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>