mmc: Move core functions to subdir

Create a "core" subdirectory to house the central bus handling
functions.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 7d98990..800425e 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -10,7 +10,7 @@
 #ifndef LINUX_MMC_CARD_H
 #define LINUX_MMC_CARD_H
 
-#include <linux/mmc/mmc.h>
+#include <linux/mmc/core.h>
 
 struct mmc_cid {
 	unsigned int		manfid;