Upstream commit cc255c76 ("libceph: implement CEPHX_V2 calculation
mode") was adjusted incorrectly: CEPH_FEATURE_CEPHX_V2 if condition got
inverted, thus breaking 4.9.144 and later kernels for all setups that
use cephx.

Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>