KVM: s390: fix and feature for kvm/next (4.3)
1. error handling for irq routes
2. Gracefully handle STP time changes
s390 supports a protocol for syncing different systems via the stp
protocol that will steer the TOD clocks to keep all participating
clocks below the round trip time between the system. In case of
specific out of sync event Linux can opt-in to accept sync checks.
This will result in non-monotonic jumps of the TOD clock, which
Linux will correct via time offsets to keep the wall clock time
monotonic. Now: KVM guests also base their time on the host TOD,
so we need to fixup the offset for them as well.