How about setting CONFIG_MMC_RICOH_MMC?

In fact that is one of the default config settings, so even if the card 
reader was not present that option is always 'y'

config MMC_RICOH_MMC
         bool "Ricoh MMC Controller Disabler  (EXPERIMENTAL)"
         depends on MMC_SDHCI_PCI
         help
           This adds a pci quirk to disable Ricoh MMC Controller. This
           proprietary controller is unnecessary because the SDHCI driver
           supports MMC cards on the SD controller, but if it is not
           disabled, it will steal the MMC cards away - rendering them
           useless. It is safe to select this even if you don't
           have a Ricoh based card reader.