mmc: Add a new callback function to perform the 74 clocks cycle sequence

Add a new callback function *send_init_stream* which start a sequence of
at least 74 clock cycles.
The mmc core uses *mmc_send_init_stream* in order to invoke the callback
function. This will be used during power cycle where the specification
requires such a sequence after power up.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
diff --git a/include/mmc.h b/include/mmc.h
index e524963..bd096ae 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -361,6 +361,14 @@
 	int (*set_ios)(struct udevice *dev);
 
 	/**
+	 * send_init_stream() - send the initialization stream: 74 clock cycles
+	 * This is used after power up before sending the first command
+	 *
+	 * @dev:	Device to update
+	 */
+	void (*send_init_stream)(struct udevice *dev);
+
+	/**
 	 * get_cd() - See whether a card is present
 	 *
 	 * @dev:	Device to check
@@ -382,11 +390,13 @@
 int dm_mmc_send_cmd(struct udevice *dev, struct mmc_cmd *cmd,
 		    struct mmc_data *data);
 int dm_mmc_set_ios(struct udevice *dev);
+void dm_mmc_send_init_stream(struct udevice *dev);
 int dm_mmc_get_cd(struct udevice *dev);
 int dm_mmc_get_wp(struct udevice *dev);
 
 /* Transition functions for compatibility */
 int mmc_set_ios(struct mmc *mmc);
+void mmc_send_init_stream(struct mmc *mmc);
 int mmc_getcd(struct mmc *mmc);
 int mmc_getwp(struct mmc *mmc);