hw/loader: Pass ELFDATA endian order argument to load_elf_as()

hw/loader: Pass ELFDATA endian order argument to load_elf_as()

Rather than passing a boolean 'is_big_endian' argument,
directly pass the ELFDATA, which can be unspecified using
the ELFDATANONE value.

Update the call sites:
  0 -> ELFDATA2LSB
  1 -> ELFDATA2MSB

Note, this allow removing the target_words_bigendian() call
in the GENERIC_LOADER device, where we pass ELFDATANONE.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250127113824.50177-6-philmd@linaro.org>