HDFS-15950. Remove unused hdfs.proto import (#2858)

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/inotify.proto

@@ -32,7 +32,6 @@ package hadoop.hdfs;
 
 import "acl.proto";
 import "xattr.proto";
-import "hdfs.proto";
 
 enum EventType {
   EVENT_CREATE = 0x0;