cephfs: fix omap deletion in DeleteSnapshot
cephfs: fix omap deletion in DeleteSnapshot

The omap is stored with the requested
snapshot name not with the subvolume
snapshotname. This fix uses the correct
snapshot request name to cleanup the omap
once the subvolume snapshot is deleted.

fixes: #2974

Signed-off-by: Madhu Rajanna <60fbf37a92c2a0908e31296d18dadbec5a4dae17@gmail.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi