bsps/stm32h7: disable MPU alignment for M4-based BSP variants

There is no point in wasting precious memory space on enforced section
alignment for the purpose of MPU which is not implemented on M4 core
anyway.

spec/build/bsps/arm/stm32h7/optenmpualign.yml

@@ -7,6 +7,10 @@ build-type: option
 copyrights:
 - Copyright (C) 2020 embedded brains GmbH & Co. KG
 default:
+- enabled-by:
+  - arm/stm32h747i-disco-m4
+  - arm/stm32h757i-eval-m4
+  value: false
 - enabled-by: true
   value: true
 description: |