ceph: update csi image version to 3.1.0 in spec.go
ceph: update csi image version to 3.1.0 in spec.go

Signed-off-by: Humble Chirammal <dc8ba7e82a7df22725dedec9b10c7aaab9ec713f@redhat.com>

rook/rook,rook/nfs,rook/rook,rook/nfs,rook/rook,rook/rook,rook/nfs,rook/rook