builder/amazon: alphabetize some things

builder/amazon/common/block_device.go

@@ -6,14 +6,14 @@ import (
 
 // BlockDevice
 type BlockDevice struct {
+	DeleteOnTermination bool   `mapstructure:"delete_on_termination"`
 	DeviceName          string `mapstructure:"device_name"`
-	VirtualName         string `mapstructure:"virtual_name"`
+	IOPS                int64  `mapstructure:"iops"`
+	NoDevice            bool   `mapstructure:"no_device"`
 	SnapshotId          string `mapstructure:"snapshot_id"`
+	VirtualName         string `mapstructure:"virtual_name"`
 	VolumeType          string `mapstructure:"volume_type"`
 	VolumeSize          int64  `mapstructure:"volume_size"`
-	DeleteOnTermination bool   `mapstructure:"delete_on_termination"`
-	IOPS                int64  `mapstructure:"iops"`
-	NoDevice            bool   `mapstructure:"no_device"`
 }
 
 type BlockDevices struct {