imx: imx8ulp: configure XRDC for DRAM access from S400

Need to add DRAM access permission for S400, as S400 needs to access
it When SPL calls image authentication

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8ulp/rdc.c b/arch/arm/mach-imx/imx8ulp/rdc.c
index c36c0ac..86310ca 100644
--- a/arch/arm/mach-imx/imx8ulp/rdc.c
+++ b/arch/arm/mach-imx/imx8ulp/rdc.c
@@ -286,6 +286,11 @@
 	xrdc_config_mrc_dx_perm(5, 0, 1, 1);
 	xrdc_config_mrc_w3_w4(5, 0, 0x0, 0x80000FFF);
 
+	/* Set MRC6 for DDR access from Sentinel */
+	xrdc_config_mrc_w0_w1(6, 0, CFG_SYS_SDRAM_BASE, PHYS_SDRAM_SIZE);
+	xrdc_config_mrc_dx_perm(6, 0, 4, 1);
+	xrdc_config_mrc_w3_w4(6, 0, 0x0, 0x80000FFF);
+
 	/* The MRC8 is for SRAM1 */
 	xrdc_config_mrc_w0_w1(8, 0, 0x21000000, 0x10000);
 	/* Allow for all domains: So domain 2/3 (HIFI DSP/LPAV) is ok to access */