clk: imx: scu: Add A72 frequency scaling support

Add A72 clock to support cpufreq on A72 cluster.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>