block/rbd: bump librbd requirement to luminous release

Ceph Luminous (version 12.2.z) is almost 4 years old at this point.
Bump the requirement to get rid of the ifdef'ry in the code.
Qemu 6.1 dropped the support for RHEL-7 which was the last supported
OS that required an older librbd.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Message-Id: <20210702172356.11574-2-idryomov@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2 files changed