os_time_get_absolute_timeout(0) returns current time, while kernel
driver expects 0 as value to poll BO status and return immediately.
Fix it by setting abs_timeout to 0 if timeout_ns is 0

Reviewed-by: Qiang Yu <yuq825@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>