nfs: remove WARN_ON_ONCE from nfs_direct_good_bytes
nfs: remove WARN_ON_ONCE from nfs_direct_good_bytes

For flexfiles driver, we might choose to read from mirror index other
than 0 while mirror_count is always 1 for read.

Reported-by: Jean Spector <51f8b1fa9b424745378826727452997ee2a7c3d7@primarydata.com>
Cc: <4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org> # v3.19+
Cc: Weston Andros Adamson <2782014720c8dba08f7eb23e9f1d190c445c0c94@primarydata.com>
Signed-off-by: Peng Tao <4fb2b5cc20694ed9d470f738b651303a1e636b2d@primarydata.com>
Signed-off-by: Trond Myklebust <cc958843532c615cbd4920e868f78c7985331a5a@primarydata.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs