misc: imx: S400_API: Move S400 MU and API to a common place

Since iMX9 uses S401 which shares the API with iMX8ULP. So move S400
MU driver and API to a common place and selected by CONFIG_IMX_SENTINEL

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>

arch/arm/include/asm/global_data.h

@@ -90,7 +90,7 @@ struct arch_global_data {
 	struct udevice *scu_dev;
 #endif
 
-#ifdef CONFIG_ARCH_IMX8ULP
+#ifdef CONFIG_IMX_SENTINEL
 	struct udevice *s400_dev;
 #endif
 

arch/arm/include/asm/mach-imx/mu_hal.h

@@ -3,8 +3,8 @@
  * Copyright 2021 NXP
  */
 
-#ifndef __IMX8ULP_MU_HAL_H__
-#define __IMX8ULP_MU_HAL_H__
+#ifndef __SNT_MU_HAL_H__
+#define __SNT_MU_HAL_H__
 
 void mu_hal_init(ulong base);
 int mu_hal_sendmsg(ulong base, u32 reg_index, u32 msg);