hw/sparc: Mark devices as big-endian

hw/sparc: Mark devices as big-endian

These devices are only used by the SPARC targets, which are
only built as big-endian. Therefore the DEVICE_NATIVE_ENDIAN
definition expand to DEVICE_BIG_ENDIAN (besides, the
DEVICE_LITTLE_ENDIAN case isn't tested). Simplify directly
using DEVICE_BIG_ENDIAN.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20241106184612.71897-6-philmd@linaro.org>