Migrate __warn_deprecated -> __deprecated

Use the new __deprecated macro from the generic cdefs header and remove
the deprecated __warn_deprecated.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 687c221..f37a80f 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -273,7 +273,7 @@
  * haven't migrated to the new platform API to compile on platforms which
  * have the compatibility layer disabled.
  */
-unsigned int platform_get_core_pos(unsigned long mpidr) __warn_deprecated;
+unsigned int platform_get_core_pos(unsigned long mpidr) __deprecated;
 
 #endif /* __ENABLE_PLAT_COMPAT__ */
 #endif /* __PLATFORM_H__ */