drm/i915/gvt: Fix gvt scheduler interval time

Fix to correctly assign 1ms for gvt scheduler interval time,
as previous code using HZ is pretty broken. And use no delay
for start gvt scheduler function.

Fixes: 4b63960e ("drm/i915/gvt: vGPU schedule policy framework")
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: stable@vger.kernel.org # v4.10+
Acked-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>