Add the option mmc_core.removable=0 to the kernel boot options in the grub config (for GRUB 2: edit /etc/default/grub and add it to GRUB_CMDLINE_LINUX, then run sudo update-grub; for GRUB 1: edit /boot/grub/menu.lst and add it to the end of the line beginning with # kopt=, then run sudo update-grub).
Add the option mmc_core. removable= 0 to the kernel boot options in the grub config (for GRUB 2: edit /etc/default/grub and add it to GRUB_CMDLINE_LINUX, then run sudo update-grub; for GRUB 1: edit /boot/grub/menu.lst and add it to the end of the line beginning with # kopt=, then run sudo update-grub).