drm/hisilicon: fixed the wrong resolution configurations

The maximum resolution supported by hibmc is 1920 * 1200 instead of
1920 * 1440, this patch fixed this problem

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Gong junjie <gongjunjie2@huawei.com>
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1578023756-46567-1-git-send-email-tiantao6@hisilicon.com