mmc: mediatek: add pre_enable() and post_disable() hook function

CQHCI_ENABLE bit in CQHCI_CFG should be disabled
after msdc_cqe_disable(), and should be enabled before
msdc_ceq_enable() for MTK platform.
Add hook functions for cqhci_host_ops->pre_enable() and
cqhci_host_ops->post_disable().

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/1598520783-25250-3-git-send-email-chun-hung.wu@mediatek.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>