pnfs/flexfiles: LAYOUTSTATS ii_count should be ops instead of bytes

Turned out I misinterpreted the spec...

Cc: Tom Haynes <thomas.haynes@primarydata.com>
Reported-by: Jean Spector <jean@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>