Platform: Fix warnings in RSS build

Fixes some miscellaneous warnings that occur in the RSS build.

Signed-off-by: Jamie Fox <jamie.fox@arm.com>
Change-Id: I040a9156018517f25acf6e4ce9ae2fab0e0c3d27
diff --git a/secure_fw/spm/include/utilities.h b/secure_fw/spm/include/utilities.h
index 87e5c16..fc45890 100644
--- a/secure_fw/spm/include/utilities.h
+++ b/secure_fw/spm/include/utilities.h
@@ -47,10 +47,14 @@
 /* Runtime memory operations forwarding */
 #ifndef spm_memcpy
 #define spm_memcpy memcpy
+#else
+void *spm_memcpy(void *dest, const void *src, size_t n);
 #endif /* spm_memcpy */
 
 #ifndef spm_memset
 #define spm_memset memset
+#else
+void *spm_memset(void *s, int c, size_t n);
 #endif /* spm_memset */
 
 #endif /* __TFM_UTILS_H__ */