KVM: s390: Fix access to CR6 in TPI handler

The TPI handler currently uses vcpu->run->s.regs.crs[6] to get the current
value of CR6. I think this is wrong, because vcpu->run->s.regs.crs is
only updated when kvm_arch_vcpu_ioctl_run() drops back to userspace.
So let's change the TPI handler to use vcpu->arch.sie_block->gcr[6] instead.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>