phy: rockchip-emmc: retry calpad busy trimming

It turns out that 5us isn't enough for all cases, so let's
retry some more times to wait for caldone.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>