arm: imx8ulp: release and configure XRDC at early phase

arm: imx8ulp: release and configure XRDC at early phase

Since S400 will set the memory of SPL image to R/X. We can't write
to any data in SPL image.

1. Set the parameters save/restore only for u-boot, not for SPL. to
   avoid write data.
2. Not use MU DM driver but directly call MU API to send release XRDC
   to S400 at early phase.
3. Configure the SPL image memory of SRAM2 to writable (R/W/X)

Signed-off-by: Ye Li <[email protected]>
Signed-off-by: Peng Fan <[email protected]>