mmc: sdhci-of-arasan: Properly set corecfg_clockmultiplier on rk3399

corecfg_clockmultiplier indicates clock multiplier value of
programmable clock generator which should be the same value
of SDHCI_CAPABILITIES_1. The default value of the register,
corecfg_clockmultiplier, is 0x10. But actually it is a mistake
by designer as our intention was to set it to be zero which
means we don't support programmable clock generator. So we have
to make it to be zero on bootloader which seems work fine until
now. But now we find an issue that when deploying genpd support
for it, the remove callback will trigger the genpd to poweroff the
power domain for sdhci-of-arasan which manage the controller, phy
and corecfg_* stuff.

So when we do bind/unbind the driver, we have already reinit
the controller and phy, but without doing that for corecfg_*.
Regarding to only the corecfg_clockmultipler is wrong, let's
fix it by explicitly marking it to be zero when probing. With
this change, we could do bind/unbind successfully.

Reported-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Tested-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>