drm/mediatek/dp: fix memory leak on ->get_edid callback audio detection

The sads returned by drm_edid_to_sad() needs to be freed.

Fixes: e71a8ebb ("drm/mediatek: dp: Audio support for MT8195")
Cc: Guillaume Ranquet <granquet@baylibre.com>
Cc: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-mediatek@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: <stable@vger.kernel.org> # v6.1+
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20230914155317.2511876-1-jani.nikula@intel.com/Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_dp.c

@@ -2049,7 +2049,6 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 	bool enabled = mtk_dp->enabled;
 	struct edid *new_edid = NULL;
 	struct mtk_dp_audio_cfg *audio_caps = &mtk_dp->info.audio_cur_cfg;
-	struct cea_sad *sads;
 
 	if (!enabled) {
 		drm_atomic_bridge_chain_pre_enable(bridge, connector->state->state);
@@ -2068,7 +2067,11 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 	}
 
 	if (new_edid) {
+		struct cea_sad *sads;
+
 		audio_caps->sad_count = drm_edid_to_sad(new_edid, &sads);
+		kfree(sads);
+
 		audio_caps->detect_monitor = drm_detect_monitor_audio(new_edid);
 	}