This resolution isn’t supported at this time.
There were problems with some of the VESA resolutions and the SoC provider recommended discontinuing them.
However, I can now see the following modes are now supported up-stream:
640x480p60hz, 800x600p60hz, 800x480p60hz, 852x480p60hz,
854x480p60hz, 1024x600p60hz, 1024x768p60hz, 1152x864p75hz,
1280x768p60hz, 1280x800p60hz, 1280x960p60hz, 1280x1024p60hz,
1360x768p60hz, 1366x768p60hz, 1400x1050p60hz, 1440x900p60hz,
1600x900p60hz, 1600x1200p60hz, 1680x1050p60hz, 1920x1200p60hz,
On the next kernel sync with AML, we will include support for more resolutions.