drm/msm/dpu: fix BGR565 vs RGB565 confusion

The component order between the two was swapped, resulting in incorrect
color when games with 565 visual hit the overlay path instead of GPU
composition.

Fixes: 25fdd593

 ("drm/msm: Add SDM845 DPU support")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>