Revert "arch: arm: mpu: fix erratum 1013783-B"

This reverts commit 983b1d0.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>

Author: manuargue

arch/arm/core/mpu/arm_mpu_regions.c

@@ -1,6 +1,5 @@
 /*
  * Copyright (c) 2017 Linaro Limited.
- * Copyright 2025 NXP
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -11,18 +10,8 @@
 #include <zephyr/arch/arm/cortex_m/arm_mpu_mem_cfg.h>
 
 static const struct arm_mpu_region mpu_regions[] = {
-
-#if defined(CONFIG_CPU_CORTEX_M7) && defined(CONFIG_CPU_HAS_ARM_MPU) && \
-	defined(CONFIG_CPU_HAS_DCACHE)
-	/* Erratum 1013783-B (SDEN-1068427): use first region to prevent speculative access
-	 * in entire memory space
-	 */
-	MPU_REGION_ENTRY("BACKGROUND",
-			 0,
-			 {REGION_4G | MPU_RASR_XN_Msk | P_NA_U_NA_Msk}),
-#endif
-
 #ifdef CONFIG_XIP
+	/* Region 0 */
 	MPU_REGION_ENTRY("FLASH_0",
 			 CONFIG_FLASH_BASE_ADDRESS,
 #if defined(CONFIG_ARMV8_M_BASELINE) || defined(CONFIG_ARMV8_M_MAINLINE)
@@ -33,6 +22,7 @@ static const struct arm_mpu_region mpu_regions[] = {
 #endif
 #endif
 
+	/* Region 1 */
 	MPU_REGION_ENTRY("SRAM_0",
 			 CONFIG_SRAM_BASE_ADDRESS,
 #if defined(CONFIG_ARMV8_M_BASELINE) || defined(CONFIG_ARMV8_M_MAINLINE)