meta.GetObjectMap code bug

**Describe the bug**
file meta/object.go：49
```
func (m *Meta) GetObjectMap(bucketName, objectName string) (objMap *ObjMap, err error) {
	m.Client.GetObjectMap(bucketName, objectName)
	return
}
```
should be
```
func (m *Meta) GetObjectMap(bucketName, objectName string) (objMap *ObjMap, err error) {
	return m.Client.GetObjectMap(bucketName, objectName)
}
```
]
