mmc: sdhci-pci: Remove set-but-unused variable.

drivers/mmc/host/sdhci-pci.c: In function ‘sdhci_pci_probe_slot’:
drivers/mmc/host/sdhci-pci.c:913:18: warning: variable ‘addr’ set but
not used [-Wunused-but-set-variable]

Signed-off-by: Chris Ball <cjb@laptop.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>