configs: sandbox64: Enable video 16bpp and 24bpp support

Align the sandbox64 defconfig with sandbox defconfig. Enable missing
16bpp and 24bpp video support. This fixes ut_dm_dm_test_video_bmp16
and ut_dm_dm_test_video_bmp24 tests .

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Simon Glass <sjg@chromium.org>