Add i.MX7 SNVS RTC clock.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Acked-by: NDong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>