lk: include: Add support for boot device detection.

Change-Id: I6606295ac395ed9f43edf2e0c637dd0b46b199f4
diff --git a/include/target.h b/include/target.h
index 00f5885..c973a61 100644
--- a/include/target.h
+++ b/include/target.h
@@ -51,5 +51,14 @@
 void *target_mmc_device();
 
 bool target_display_panel_node(char *pbuf, uint16_t buf_size);
+uint32_t target_get_boot_device();
+
+/* Boot device */
+enum boot_device
+{
+	BOOT_DEFAULT=0,
+	BOOT_EMMC=2,
+	BOOT_UFS=4,
+};
 
 #endif