MLK-17696: Change resource from PID_0 to SYSTEM for scu control.

MLK-17696: Change resource from PID_0 to SYSTEM for scu control.

Syncs with the following change in scfw.

    Author: Chuck Cannon <chuck.cannon@freescale.com>
    Date:   Mon Mar 5 07:44:27 2018 -0600

    SCF-22: Move SCU controls to SYSTEM. Allows AP to use SCU temp
    sensor.

BuildInfo:
  - SCFW e56d4c0a, IMX-MKIMAGE d4e440b2, ATF 4af5ca0
  - U-Boot 2017.03-imx_v2017.03_4.9.51_imx8_beta2+gf195c38

Tested-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Nitin Garg <nitin.garg@nxp.com>
Signed-off-by: Adriana Reus <adriana.reus@nxp.com>