Add i.MX8MM clock definition. Signed-off-by: Peng Fan <peng.fan@nxp.com> Signed-off-by: Bai Ping <ping.bai@nxp.com> Signed-off-by: Fugang Duan <fugang.duan@nxp.com> Signed-off-by: Cosmin-Gabriel Samoila <cosmin.samoila@nxp.com> Signed-off-by: Anson Huang <Anson.Huang@nxp.com> Reviewed-by: Bai Ping <ping.bai@nxp.com>