mmc: sdhci-pci: Do not default to 33 Ohm driver strength for Intel SPT

In some cases, the stronger 33 Ohm driver strength must not be used
so it is not a suitable default.  Change it to the standard default
50 Ohm value.

The patch applies to v4.2+ except the file name changed.  It is
drivers/mmc/host/sdhci-pci.c prior to v.4.4.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>