imx: imx8ulp: Get chip revision from Sentinel

In both SPL and u-boot, after probing the S400 MU, get the chip revision,
lifecycle and UID from Sentinel.
Update get_cpu_rev to use the chip revision not hard coded it for A0

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/imx8ulp_evk/spl.c b/board/freescale/imx8ulp_evk/spl.c
index e672f6e..2a96bd0 100644
--- a/board/freescale/imx8ulp_evk/spl.c
+++ b/board/freescale/imx8ulp_evk/spl.c
@@ -77,16 +77,12 @@
 
 void spl_board_init(void)
 {
-	struct udevice *dev;
 	u32 res;
 	int ret;
 
-	uclass_find_first_device(UCLASS_MISC, &dev);
-
-	for (; dev; uclass_find_next_device(&dev)) {
-		if (device_probe(dev))
-			continue;
-	}
+	ret = imx8ulp_dm_post_init();
+	if (ret)
+		return;
 
 	board_early_init_f();