rbd: fix naming convention violations in snapshot.go
rbd: fix naming convention violations in snapshot.go

Fix up variable names that don't meet Go standards.

Command: gofmt -w -r 'c_snapname -> cSnapName' rbd/snapshot.go

Signed-off-by: John Mulligan <eda8ad33169deab44f9fe65847f99e368da6c91b@redhat.com>

ceph/go-ceph,ceph/go-ceph,ceph/go-ceph