mmc: sdhci-pci: Convert to use managed functions (part2)

The commit 52ac7acf ("mmc: sdhci-pci: Convert to use managed functions
pcim_* and devm_*") converted ->probe() / ->remove() functions to use device
managed resource API. Here is a follow up to cover sdhci_pci_probe_slot() and
sdhci_pci_remove_slot().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>