mmc: sdhci-pci: Fix default d3_retune for Intel host controllers

The default for d3_retune is true, but that was not being set in all cases,
which results in eMMC errors because re-tuning has not been done.
Fix by initializing d3_retune to true.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: c959a6b0 ("mmc: sdhci-pci: Don't re-tune with runtime pm for some Intel devices")
Cc: stable@vger.kernel.org # v4.12+
Reported-and-tested-by: ojab <ojab@ojab.ru>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>