mmc: sdhci-pci: Fix BYT sd card getting stuck in runtime suspend

A host controller for a SD card may need a GPIO for card detect in order
to wake up from runtime suspend when a card is inserted.  If that GPIO is
not configured, then the host controller will not wake up.  Fix that for
the affected devices by not enabling runtime PM unless the GPIO is
successfully set up.

This affects BYT sd card host controller which had runtime PM enabled from
v3.11.  For completeness, the MFD sd card host controller is flagged also.

The original patch before rebasing (see link below) was tested on v3.11.10
and v3.12.4 although the patch applied with some offsets and fuzz.  The
original patch is here:

    http://marc.info/?l=linux-mmc&m=138676702327057

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable <stable@vger.kernel.org> # 3.11+
Signed-off-by: Chris Ball <chris@printf.net>