nfsd: fix corrupted reply to badly ordered compound

nfsd: fix corrupted reply to badly ordered compound

[ Upstream commit 5b7b15aee641904ae269be9846610a3950cbd64c ]

We're encoding a single op in the reply but leaving the number of ops
zero, so the reply makes no sense.

Somewhat academic as this isn't a case any real client will hit, though
in theory perhaps that could change in a future protocol extension.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>