feat(fvp): implement platform API for load and auth image

Introduce and implement a stub implementation of
`plat_lfa_load_auth_image()` for the FVP platform. For AEM FVP, no
actual image loading or authentication is required as of now, as
images are assumed to be pre-loaded and authenticated.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I82e51f5d18db6d5b9c61f9081b451619d761abe8
diff --git a/include/plat/common/plat_lfa.h b/include/plat/common/plat_lfa.h
index 7760d10..fa7c2f9 100644
--- a/include/plat/common/plat_lfa.h
+++ b/include/plat/common/plat_lfa.h
@@ -20,5 +20,6 @@
 uint32_t plat_lfa_get_components(plat_lfa_component_info_t **components);
 bool is_plat_lfa_activation_pending(uint32_t lfa_component_id);
 int plat_lfa_cancel(uint32_t lfa_component_id);
+int plat_lfa_load_auth_image(uint32_t lfa_component_id);
 
 #endif /* PLAT_LFA_H */