kvm: Correctly handle the return value from handleIpr(Read|Write)
kvm: Correctly handle the return value from handleIpr(Read|Write)

The KVM base class incorrectly assumed that handleIprRead and
handleIprWrite both return ticks. This is not the case, instead they
return cycles. This changeset converts the returned cycles to ticks
when handling IPR accesses.

haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5