nfsd/nfs3: remove unused macro nfsd3_fhandleres

The macro is unused, remove it to tame gcc warning:
fs/nfsd/nfs3proc.c:702:0: warning: macro "nfsd3_fhandleres" is not used
[-Wunused-macros]

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: linux-nfs@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>