mmc: core: Add cache control for eMMC4.5 device

This patch adds cache feature of eMMC4.5 Spec.
If device supports cache capability, host can utilize some specific
operations.

Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index e918120..67bac37 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -177,6 +177,8 @@
 extern void mmc_do_release_host(struct mmc_host *host);
 extern int mmc_try_claim_host(struct mmc_host *host);
 
+extern int mmc_flush_cache(struct mmc_card *);
+
 /**
  *	mmc_claim_host - exclusively claim a host
  *	@host: mmc host to claim