If enable Ceph MDS and RBD services, they are not conflicting
with Swift service.
Fix the check condition to make sure both Ceph and Swift exist.
Closes-Bug: #1747592
Change-Id: Icc6806125ce72992f7dff00c30d591ffb737a0c6
Signed-off-by: Tone.Zhang <tone.zhang@arm.com>