MTP: Add support for dynamically adding and removing storage units

BUG: 3402847

Change-Id: I7da266061d949abcb6bb11c6faaa47b5e4a2a977
diff --git a/media/mtp/mtp.h b/media/mtp/mtp.h
index 8bc2e22..6fedc16 100644
--- a/media/mtp/mtp.h
+++ b/media/mtp/mtp.h
@@ -22,6 +22,8 @@
 
 #define MTP_STANDARD_VERSION            100
 
+#define MTP_FIRST_STORAGE_ID            0x00010001
+
 // Container Types
 #define MTP_CONTAINER_TYPE_UNDEFINED    0
 #define MTP_CONTAINER_TYPE_COMMAND      1