CorebootPayloadPkg: Use correct BytesPerScanLine
    
    Fetch BytesPerScanLine from coreboot table to reflect how the actual
    framebuffer is set up instead of guessing it from the horizontal
    resolution.
    
    This fixes a garbled display when HorizontalResolution * (BitsPerPixel
    / 8) and pFbInfo->BytesPerScanLine don't match.
    
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
    Reviewed-by: Benjamin You <benjamin.you@intel.com>