feat(fwu): add a function to pass metadata structure to platforms

Add a helper function to pass the metadata structure to the
platforms. Platforms can then read the metadata structure and pass the
boot index value, i.e. the bank(partition) from which the firmware
images were booted, to the Update Agent.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Change-Id: I571179b9baa0fbc4d0f08d7a6e3b50c0c7165c5c
diff --git a/include/drivers/fwu/fwu.h b/include/drivers/fwu/fwu.h
index ae06da9..9f18e22 100644
--- a/include/drivers/fwu/fwu.h
+++ b/include/drivers/fwu/fwu.h
@@ -11,5 +11,6 @@
 
 void fwu_init(void);
 bool fwu_is_trial_run_state(void);
+const struct fwu_metadata *fwu_get_metadata(void);
 
 #endif /* FWU_H */