mmc: mediatek: command queue support

Support command queue for mt6779 platform.
a. Add msdc_set_busy_timeout() to calculate emmc write timeout.
b. Connect mtk msdc driver to cqhci driver through
   host->cq_host->ops = &msdc_cmdq_ops;
c. msdc_cmdq_irq() will link up with cqchi_irq(). Besides, it provides
   more irq error messages like RSPCRCERR/CMDTO/DATACRCERR/DATTMO.
d. Select kernel config MMC_CQHCI for MMC_MTK

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Acked-by: Yong Mao <yong.mao@mediatek.com>
Link: https://lore.kernel.org/r/1595205759-5825-4-git-send-email-chun-hung.wu@mediatek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>