get_primary_vcpu
vcpu_from_vid
This patch simplifies `get_primary_vcpu` and `vcpu_from_vid`. The target_vcpu could be get from the index directly. Tracked-On: #1842 Signed-off-by: Shiqing Gao <shiqing.gao@intel.com> Acked-by: Eddie Dong <eddie.dong@intel.com>