stm32cube: stm32n6: Add fsbl fix

To use FSBL mode, add the following fix:
-Remove CMSE_NS_ENTRY modifier, which requires enabling
CONFIG_ARM_FIRMWARE_HAS_SECURE_ENTRY_FUNCS

Signed-off-by: Guillaume Gautier <[email protected]>

Author: gautierg-st

stm32cube/stm32n6xx/README

@@ -47,4 +47,10 @@ Patch List:
     Impacted files:
      drivers/include/Legacy/stm32_hal_legacy.h
 
+   *Fix FSBL configuration
+    -Remove CMSE_NS_ENTRY modifier, which requires enabling CONFIG_ARM_FIRMWARE_HAS_SECURE_ENTRY_FUNCS
+     which we don't need right now.
+    Impacted files:
+    -soc/system_stm32n6xx_fsbl.c
+
    See release_note.html from STM32Cube

stm32cube/stm32n6xx/soc/system_stm32n6xx_fsbl.c

@@ -482,7 +482,7 @@ void SystemCoreClockUpdate(void)
   *         other parameters.
   * @retval SystemCoreClock value
   */
-CMSE_NS_ENTRY uint32_t SECURE_SystemCoreClockUpdate(void)
+uint32_t SECURE_SystemCoreClockUpdate(void)
 {
   SystemCoreClockUpdate();