nfsd: remove redundant assignment to variable len

Variable len is being assigned a value zero and this is never
read, it is being re-assigned later. The assignment is redundant
and can be removed.

Cleans up clang scan-build warning:
fs/nfsd/nfsctl.c:636:2: warning: Value stored to 'len' is never read
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfsctl.c

@@ -633,7 +633,6 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 	}
 
 	/* Now write current state into reply buffer */
-	len = 0;
 	sep = "";
 	remaining = SIMPLE_TRANSACTION_LIMIT;
 	for (num=2 ; num <= 4 ; num++) {