nfsd: kill unused macro definition

These macros had never been used for several years.
So, remove them.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 54b60bf..c4f2b0f 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -148,7 +148,7 @@
 /* hash table for nfs4_file */
 #define FILE_HASH_BITS                   8
 #define FILE_HASH_SIZE                  (1 << FILE_HASH_BITS)
-#define FILE_HASH_MASK                  (FILE_HASH_SIZE - 1)
+
 /* hash table for (open)nfs4_stateid */
 #define STATEID_HASH_BITS              10
 #define STATEID_HASH_SIZE              (1 << STATEID_HASH_BITS)