drm/i915/gvt: Fix vGPU sched timeslice calculation warning
Fix below warning by using proper ktime helper to calculate timeslice.
CHECK drivers/gpu/drm/i915//gvt/sched_policy.c
drivers/gpu/drm/i915//gvt/sched_policy.c:108 gvt_balance_timeslice() debug: sval_binop_signed: invalid divide LLONG_MIN/-1
drivers/gpu/drm/i915//gvt/sched_policy.c:108 gvt_balance_timeslice() debug: sval_binop_signed: invalid divide LLONG_MIN/-1
Reviewed-by: Zhi Wang <[email protected]>
Signed-off-by: Zhenyu Wang <[email protected]>