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/host.h b/include/linux/mmc/host.h
index 6ea3c0e..43bf6a5 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -10,7 +10,7 @@
 #ifndef LINUX_MMC_HOST_H
 #define LINUX_MMC_HOST_H
 
-#include <linux/mmc/mmc.h>
+#include <linux/mmc/core.h>
 
 struct mmc_ios {
 	unsigned int	clock;			/* clock rate */