hw/arm/armv7m: Expose and access System Control Space as little endian

hw/arm/armv7m: Expose and access System Control Space as little endian

We only build ARM system emulators using little
endianness, so the MO_TE definition always expands to
MO_LE, and DEVICE_TARGET_ENDIAN to DEVICE_LITTLE_ENDIAN.

Replace the definitions by their expanded value, making
it closer to the Armv7-M Architecture Reference Manual
(ARM DDI 0403E) description:

  The System Control Space (SCS, address range 0xE000E000 to
  0xE000EFFF) is a memory-mapped 4KB address space that provides
  32-bit registers for configuration, status reporting and control.
  All accesses to the SCS are little endian.

Fixes: d5d680cacc ("memory: Access MemoryRegion with endianness")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250312104821.1012-1-philmd@linaro.org>