imx8ulp: Use DGO_GP5 to get boot config

Since CMC1 MR0 only reflects high 16 bits boot cfg used for AP domian,
it does not connect to low 16 bits for RTD. So we can't get the correct
boot mode.
Change to use DGO_GP5 of SEC_SIM which is set by ROM.
Signed-off-by: NYe Li <ye.li@nxp.com>

arch/arm/mach-imx/imx8ulp/soc.c

@@ -120,7 +120,7 @@ enum bt_mode get_boot_mode(void)
 {
 	u32 bt0_cfg = 0;
 
-	bt0_cfg = readl(CMC1_BASE_ADDR + 0xa0);
+	bt0_cfg = readl(SIM_SEC_BASE_ADDR + 0x24);
 	bt0_cfg &= (BT0CFG_LPBOOT_MASK | BT0CFG_DUALBOOT_MASK);
 
 	if (!(bt0_cfg & BT0CFG_LPBOOT_MASK)) {