bootstd: Add an MMC hunter

Add a hunter for MMC. This doesn't do anything at present, since MMC is
currently set up when U-Boot starts. If MMC moves to lazy init then we can
add a hunter function.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/mmc_bootdev.c b/drivers/mmc/mmc_bootdev.c
index 037b67b..300208f 100644
--- a/drivers/mmc/mmc_bootdev.c
+++ b/drivers/mmc/mmc_bootdev.c
@@ -35,3 +35,9 @@
 	.bind		= mmc_bootdev_bind,
 	.of_match	= mmc_bootdev_ids,
 };
+
+BOOTDEV_HUNTER(mmc_bootdev_hunter) = {
+	.prio		= BOOTDEVP_0_INTERNAL_FAST,
+	.uclass		= UCLASS_MMC,
+	.drv		= DM_DRIVER_REF(mmc_bootdev),
+};