drm/bridge: it6505: Fix return value check for pm_runtime_get_sync

`pm_runtime_get_sync` may return 1 on success. Fix the `if` statement
here to make the code less confusing, even though additional calls to
`it6505_poweron` doesn't break anything when it's already powered.

This was reported by Dan Carpenter <dan.carpenter@oracle.com> in
https://lore.kernel.org/all/Y1fMCs6VnxbDcB41@kili/

Fixes: 10517777 ("drm/bridge: it6505: Adapt runtime power management framework")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221027032149.2739912-1-treapking@chromium.org

drivers/gpu/drm/bridge/ite-it6505.c

@@ -2699,7 +2699,7 @@ static void it6505_extcon_work(struct work_struct *work)
 		 * pm_runtime_force_resume re-enables runtime power management.
 		 * Handling the error here to make sure the bridge is powered on.
 		 */
-		if (ret)
+		if (ret < 0)
 			it6505_poweron(it6505);
 
 		complete_all(&it6505->extcon_completion);