review: check virtiofsd directly instead of looping extra binaries

Only virtiofsd is a supported extra binary today, so drop the loop
over all configured entries in favor of checking it directly, as
suggested in review.

Signed-off-by: Akanksha Trehun <akankshatrehun@gmail.com>

Author: magic-peach

pkg/unikontainers/urunc_config.go

@@ -180,20 +180,16 @@ func LoadUruncConfig(path string) (*UruncConfig, error) {
 		}
 		cfg.Monitors[name] = mon
 	}
-	// Same issue for [extra_binaries.<name>] sections.
-	defaultBins := defaultExtraBinConfig()
-	for name, bin := range cfg.ExtraBins {
-		def, ok := defaultBins[name]
-		if !ok {
-			continue
-		}
+	// Same issue for [extra_binaries.virtiofsd], the only supported extra binary today.
+	if bin, ok := cfg.ExtraBins["virtiofsd"]; ok {
+		def := defaultExtraBinConfig()["virtiofsd"]
 		if bin.Path == "" {
 			bin.Path = def.Path
 		}
 		if bin.Options == "" {
 			bin.Options = def.Options
 		}
-		cfg.ExtraBins[name] = bin
+		cfg.ExtraBins["virtiofsd"] = bin
 	}
 
 	return cfg, nil