mpu: Support for 8 & 16 MB SRAM regions in Cortex M MPU
mpu: Support for 8 & 16 MB SRAM regions in Cortex M MPU

Added support for 8 MB MPU regions for SRAM sizes between 4 and 8 MB,
and 16 MB MPU regions for SRAM sizes between 8 and 16 MB.

Signed-off-by: Johan Öhman <bff19a8c4e2b45793b9eff7c1e342be72616abf6@softube.com>

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