Add an ICACHE section to the STM32H5 platform page. With
CONFIG_STM32_ICACHE the OTP, read-only and EDATA flash areas are mapped
non-cacheable with an MPU region, so they can be read like any other
memory.
The MPU is not applied in the HardFault and NMI handlers (HFNMIENA=0),
so these areas must not be read from NMI or HardFault context: with the
ICACHE enabled such a read raises a bus fault.
Assisted-by: Claude:claude-sonnet-5-5
Signed-off-by: Ricardo Maurizio Paul <ricardopaul@geotab.com>