Arm-Cortex-R82: Add MPU support (#1347)

* arm-cortex-r82: Add MPU support

This commit introduces support for the Memory Protection Unit (MPU)
to the ARM Cortex-R82 port. The MPU enhances system security
by allowing the definition of memory regions with specific access
permissions. The following changes have been made:
- Added MPU configuration functions in `port.c` to set up memory
  regions and their attributes.
- Updated `portASM.S` to include assembly routines for MPU
  and context switching with MPU support.
- Created `mpu_wrappers_v2_asm.c` to provide assembly wrappers for
  MPU operations.
- Updated `portmacro.h` to include MPU-related macros and definitions.
- Modified `task.h` to include MPU-related task attributes.
- Updated `CMakeLists.txt` to include the new MPU source file.
- Enhanced the `README.md` with instructions on MPU configuration.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

* cortex-r82: Minor code improvements

This commit includes minor code improvements to enhance readability
and maintainability of the Cortex-R82 port files. Changes include
refactoring variable names, optimizing comments, and improving code
structure without altering functionality.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

* tasks: Disable stack-depth check if MPU wrappers is set

This stack-depth check should not be performed for ports
where portUSING_MPU_WRAPPERS is set to 1.
In this case, pxTopOfStack and pxNewTCB->pxTopOfStack reside
in different memory regions: pxTopOfStack is in unprivileged SRAM,
while pxNewTCB->pxTopOfStack is in privileged SRAM.
This is because pxPortInitialiseStack() returns the address of
`ullContext` array rather than the decremented pxTopOfStack,
as is done in the non-MPU case.
Consequently, this check is not valid in this scenario.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

---------

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

tasks.c

@@ -1,6 +1,7 @@
 /*
  * FreeRTOS Kernel <DEVELOPMENT BRANCH>
  * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2026 Arm Limited and/or its affiliates <open-source-office@arm.com>
  *
  * SPDX-License-Identifier: MIT
  *
@@ -2007,19 +2008,19 @@ static void prvInitialiseNewTask( TaskFunction_t pxTaskCode,
             pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pxTaskCode, pvParameters );
         }
         #endif /* portHAS_STACK_OVERFLOW_CHECKING */
+
+        #if ( portSTACK_GROWTH < 0 )
+        {
+            configASSERT( ( ( portPOINTER_SIZE_TYPE ) ( pxTopOfStack - pxNewTCB->pxTopOfStack ) ) < ( ( portPOINTER_SIZE_TYPE ) uxStackDepth ) );
+        }
+        #else /* portSTACK_GROWTH */
+        {
+            configASSERT( ( ( portPOINTER_SIZE_TYPE ) ( pxNewTCB->pxTopOfStack - pxTopOfStack ) ) < ( ( portPOINTER_SIZE_TYPE ) uxStackDepth ) );
+        }
+        #endif /* portSTACK_GROWTH */
     }
     #endif /* portUSING_MPU_WRAPPERS */
 
-    #if ( portSTACK_GROWTH < 0 )
-    {
-        configASSERT( ( ( portPOINTER_SIZE_TYPE ) ( pxTopOfStack - pxNewTCB->pxTopOfStack ) ) < ( ( portPOINTER_SIZE_TYPE ) uxStackDepth ) );
-    }
-    #else /* portSTACK_GROWTH */
-    {
-        configASSERT( ( ( portPOINTER_SIZE_TYPE ) ( pxNewTCB->pxTopOfStack - pxTopOfStack ) ) < ( ( portPOINTER_SIZE_TYPE ) uxStackDepth ) );
-    }
-    #endif
-
     /* Initialize task state and task attributes. */
     #if ( configNUMBER_OF_CORES > 1 )
     {