drm/tests: Fix drm_test_fb_xrgb8888_to_xrgb2101010() on big-endian

drm/tests: Fix drm_test_fb_xrgb8888_to_xrgb2101010() on big-endian

[ Upstream commit 05663d88fd0b8ee1c54ab2d5fb36f9b6a3ed37f7 ]

Fix failures on big-endian architectures on tests cases
single_pixel_source_buffer, single_pixel_clip_rectangle,
well_known_colors and destination_pitch.

Fixes: 15bda1f8de5d ("drm/tests: Add calls to drm_fb_blit() on supported format conversion tests")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250630090054.353246-2-jose.exposito89@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>