mmc: mtk-sd: disable new_tx/rx and modify related settings for mt8189

mmc: mtk-sd: disable new_tx/rx and modify related settings for mt8189

Disable new_tx/rx to avoid data transmission instability, and adjust
.data_tune, .stop_dly_sel, and .pop_en_cnt to fit the overall
configuration after disabling new_tx/rx, making it more compatible
with mt8189.

Fixes: 846a3a2fdff5 ("mmc: mtk-sd: add support for MT8189 SoC")
Tested-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Signed-off-by: Cathy Xu <ot_cathy.xu@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>