drm/msm: provide fb_dirty implemenation

Since commit 93e81e38 ("drm/fb_helper: Minimize damage-helper
overhead") the drm_fb_helper_funcs::fb_dirty helper is required for
proper dirty/damage processing. The drm/msm driver requires that to
function to let CMD panels to work. Use simplified version of
drm_fbdev_generic_helper_fb_dirty() to fix support for CMD mode panels.

Reported-by: Degdag Mohamed <degdagmohamed@gmail.com>
Fixes: 93e81e38 ("drm/fb_helper: Minimize damage-helper overhead")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/542002/
Link: https://lore.kernel.org/r/20230612031616.3620134-1-dmitry.baryshkov@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>