Change first stage image for RPi4

Running LAVA tests shows random failures on some boards, causing several tests to fail. After investigating it, this is most likely to happen when using v2021 as first stage image to flash the device.

Since the v2022 is the first release which properly supports RPi4 switch to it as first stage release.

Signed-off-by: Walter Lozano walter.lozano@collabora.com