drm/msm/a2xx: support loading legacy (iMX) firmware

Support loading A200 firmware generated from the iMX firmware header
files. The firmware lacks protection support, however it allows GPU to
function properly while using the firmware files with clear license
which allows redistribution.

Cc: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/516443/
Link: https://lore.kernel.org/r/20230101155753.779176-1-dmitry.baryshkov@linaro.org
Signed-off-by: Rob Clark <robdclark@chromium.org>