Add a new --video_frames option to sandbox which accepts a directory path.
When set, every video test assertion writes a BMP file (frame0.bmp,
frame1.bmp, etc.) to the specified directory, allowing visual inspection
of the framebuffer at each test step.
A new video_write_bmp() function writes 16/32bpp framebuffer contents as
Windows BMP files. On startup, any existing frame*.bmp files in the
directory are removed to ensure a clean state.
Usage example:
./u-boot --video_frames /tmp/frames -c "ut dm video_text"
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
6853b7d8ad