[MMC] Deprecate "req" member of mmc_data structure.

Host drivers should now use the scatterlist rather than accessing
the request directly.  This marks the request pointer as being
deprecated so that host driver authors get a chance to fix their
drivers up before we remove this member.

include/linux/mmc/mmc.h

@@ -57,7 +57,7 @@ struct mmc_data {
 	unsigned int		timeout_clks;	/* data timeout (in clocks) */
 	unsigned int		blksz_bits;	/* data block size */
 	unsigned int		blocks;		/* number of blocks */
-	struct request		*req;		/* request structure */
+	struct request		*req __attribute__((deprecated));/* request structure (use the sg list instead) */
 	unsigned int		error;		/* data error */
 	unsigned int		flags;