There is no user of this member. Remove the dead code for good.

The removal is dependent on the previous removal of the
struct sdhci_pci_data.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20211014132613.27861-6-andriy.shevchenko@linux.intel.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>