We don't set GENHD_FL_REMOVABLE because this flag indicates that
the media may be removed while the block device persists.  Since
MMC destroys the block device when the card (media + on-board
controller) is removed, the block device will never exist without
media present.  Therefore, setting GENHD_FL_REMOVABLE would be
misleading.
Signed-off-by: Russell King <rmk@arm.linux.org.uk>