HDFS-16101. Remove unuse variable and IoException in ProvidedStorageMap. Contributed by lei w.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/ProvidedStorageMap.java

@@ -75,11 +75,9 @@ public class ProvidedStorageMap {
   private final ProvidedDescriptor providedDescriptor;
   private final DatanodeStorageInfo providedStorageInfo;
   private boolean providedEnabled;
-  private long capacity;
   private int defaultReplication;
 
-  ProvidedStorageMap(RwLock lock, BlockManager bm, Configuration conf)
-      throws IOException {
+  ProvidedStorageMap(RwLock lock, BlockManager bm, Configuration conf) {
 
     storageId = conf.get(DFSConfigKeys.DFS_PROVIDER_STORAGEUUID,
         DFSConfigKeys.DFS_PROVIDER_STORAGEUUID_DEFAULT);