nfs: remove unused label in nfs_encode_fh()

nfs: remove unused label in nfs_encode_fh()

The only reference to the label got removed, so we now get
a harmless compiler warning:

fs/nfs/export.c: In function 'nfs_encode_fh':
fs/nfs/export.c:58:1: error: label 'out' defined but not used [-Werror=unused-label]

Fixes: aaa150089465 ("nfs: remove dead code from nfs_encode_fh()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>