target: init: Add weak function for SSD keystore loading

The SSD feature is used to protect proprietary images. Loading of
keystrore should be implemented per target (if needed) and it will
be called in aboot init just before linux entry point.

Change-Id: Id45b20135c29e972a5e84942e558b623644de661
diff --git a/include/target.h b/include/target.h
index 19be4b6..b70306d 100644
--- a/include/target.h
+++ b/include/target.h
@@ -46,6 +46,7 @@
 unsigned target_baseband(void);
 void target_serialno(unsigned char *buf);
 void target_fastboot_init(void);
+void target_load_ssd_keystore(void);
 struct mmc_device *target_mmc_device();