mmc: core: Optimize size of struct mmc_queue_req

ioc_count won't be more than MMC_IOC_MAX_CMDS (255), retries won't be more
than MMC_NO_RETRIES (6), flags is newly introduced and uses only 1 bit.
Therefore let's change them all to become u8.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: liubiin

drivers/mmc/core/queue.h

@@ -69,9 +69,9 @@ struct mmc_queue_req {
 	enum mmc_drv_op		drv_op;
 	int			drv_op_result;
 	void			*drv_op_data;
-	unsigned int		ioc_count;
-	int			retries;
-	u32			flags;
+	u8			ioc_count;
+	u8			retries;
+	u8			flags;
 };
 
 struct mmc_queue {