mmc: sdhci-pci: Fix voltage switch for some Intel host controllers

Some Intel host controllers (e.g. CNP) use an ACPI device-specific method
to ensure correct voltage switching. Fix voltage switch for those, by
adding a call to the DSM.

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