Add GC9A01 model

[andelf]

Tested with a round 240x240 display with GC9A01 controller.

Testing code:

    let mut display = mipidsi::Builder::gc9a01(di)
        .with_display_size(240, 240)
        .with_color_order(mipidsi::ColorOrder::Bgr)
        .with_invert_colors(mipidsi::ColorInversion::Inverted)
        .init(&mut delay, Some(rst))
        .unwrap();
    display.set_orientation(mipidsi::Orientation::Portrait(false));
    display.clear(Rgb565::WHITE).unwrap();