pillar/kvm: add single quotes in the log to clearly see the empty string

Empty string in QEMU state is absolutely abnormal and is super
difficult to spot this problem in our enormous logging output.

Highlight the status by single quotes.

Signed-off-by: Roman Penyaev <[email protected]>

Author: rouming

pkg/pillar/hypervisor/kvm.go

@@ -973,7 +973,7 @@ func (ctx KvmContext) Info(domainName string) (int, types.SwState, error) {
 	}
 
 	if effectiveDomainState, matched := stateMap[res]; !matched {
-		return effectiveDomainID, types.BROKEN, logError("domain %s reported to be in unexpected state %s", domainName, res)
+		return effectiveDomainID, types.BROKEN, logError("domain %s reported to be in unexpected state '%s'", domainName, res)
 	} else {
 		return effectiveDomainID, effectiveDomainState, nil
 	}