clk: rockchip: fix wrong mmc phase shift for rk3228

mmc sample shift is 0 for rk3228 refer to user manaul.
So it's broken if we enable mmc tuning for rk3228.

Fixes: 307a2e9a ("clk: rockchip: add clock controller for rk3228")
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>