afs: Remove afs_zero_fid as it's not used

Remove afs_zero_fid as it's not used.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

fs/afs/yfsclient.c

@@ -15,8 +15,6 @@
 #include "xdr_fs.h"
 #include "protocol_yfs.h"
 
-static const struct afs_fid afs_zero_fid;
-
 #define xdr_size(x) (sizeof(*x) / sizeof(__be32))
 
 static void xdr_decode_YFSFid(const __be32 **_bp, struct afs_fid *fid)