Some controllers immediately report SDHCI_CLOCK_INT_STABLE after
enabling the clock even when the clock is not stable. When used in
conjunction with older/slower cards, this can result in:

    mmc0: error -84 whilst initialising SD card

When the stable reporting is known to be broken, we simply wait for the
maximum stabilization period.
Signed-off-by: Helmut Grohne <h.grohne@intenta.de>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>