treewide: initialize empty structs with var

Change-Id: I72d3993eaf5fe57c77b1dda8218e36a8cc11813d
Reviewed-on: https://review.monogon.dev/c/monogon/+/3108
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/tpm/eventlog/eventlog.go b/metropolis/pkg/tpm/eventlog/eventlog.go
index 036185a..dbfeae0 100644
--- a/metropolis/pkg/tpm/eventlog/eventlog.go
+++ b/metropolis/pkg/tpm/eventlog/eventlog.go
@@ -489,8 +489,8 @@
 	// TODO(ericchiang): Check errata? Or do we expect that to change in ways
 	// we're okay with?
 
-	specAlg := specAlgSize{}
-	e := specIDEvent{}
+	var specAlg specAlgSize
+	var e specIDEvent
 	for i := 0; i < int(header.NumAlgs); i++ {
 		if err := binary.Read(r, binary.LittleEndian, &specAlg); err != nil {
 			return nil, fmt.Errorf("reading algorithm: %v", err)