How about setting CONFIG_MMC_RICOH_MMC?
--
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.