rockchip: mmc: rockchip_dw_mmc: fix ciu clock index
The document rockchip-dw-mshc.yaml decribes a maximum of 4 clocks.
In the rockchip_dw_mmc driver the clock name in use was "fixed"
to "ciu" with index 1, but later reverted back to index 0.
The clock drivers can handle both, but the calling driver
should submit correct data as a standard practice.
Fix the "ciu" clock index by setting it back to 1.