krbdFeatures is set to zero when kernel version < 3.8, i.e. in case where
/sys/bus/rbd/supported_features is absent and we are unable to prepare
the krbd attributes based on kernel version.
When krbdFeatures is set to zero fallback to NBD only when autofallback
is turned ON.
Fixes: #2678
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
(cherry picked from commit 83cc1b0e5804b0bcd04bd5433891fa505fc51ab8)