mmc: rockchip_sdhci: Fix HS400 mode write on RK3568

Testing has shown that writing to eMMC using HS400 modes on RK3568
result in an ERROR.

Change the tap number for transmit clock to fix this.

Also stop DLL when config_dll() is called to disable DLL.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>