drm/amd/display: Write to correct dirty_rect

drm/amd/display: Write to correct dirty_rect

When FB_DAMAGE_CLIPS are provided in a non-MPO scenario, the loop does
not use the counter i. This causes the fill_dc_dity_rect() to always
fill dirty_rects[0], causing graphical artifacts when a damage clip
aware DRM client sends more than 1 damage clip.

Instead, use the flip_addrs->dirty_rect_count which is incremented by
fill_dc_dirty_rect() on a successful fill.

Fixes: 30ebe41582d1 ("drm/amd/display: add FB_DAMAGE_CLIPS support")
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/2453
Signed-off-by: Benjamin Cheng <ben@bcheng.me>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>