KVM: s390: no need to hold the kvm->mutex for floating interrupts

KVM: s390: no need to hold the kvm->mutex for floating interrupts

[ Upstream commit 69a8d456263849152826542c7cb0a164b90e68a8 ]

The kvm mutex was (probably) used to protect against cpu hotplug.
The current code no longer needs to protect against that, as we only
rely on CPU data structures that are guaranteed to be available
if we can access the CPU. (e.g. vcpu_create will put the cpu
in the array AFTER the cpu is ready).

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>