Fix comment

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/aes.c b/library/aes.c
index 22c56c9..a7be6f5 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -319,7 +319,7 @@
 static const uint32_t RT3[256] = { RT };
 #undef V
 
-#endif /* !defined(MBEDTLS_AES_DECRYPT_ALT) || !defined(MBEDTLS_AES_SETKEY_DEC) */
+#endif /* !defined(MBEDTLS_AES_DECRYPT_ALT) || !defined(MBEDTLS_AES_SETKEY_DEC_ALT) */
 
 #endif /* !MBEDTLS_AES_FEWER_TABLES */