aesni: make AESNI only operate on X86 and X86_64

Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
diff --git a/include/mbedtls/aesni.h b/include/mbedtls/aesni.h
index 9a573c4..b16ccc3 100644
--- a/include/mbedtls/aesni.h
+++ b/include/mbedtls/aesni.h
@@ -50,7 +50,8 @@
 #define MBEDTLS_HAVE_X86
 #endif
 
-#if defined(MBEDTLS_AESNI_C)
+#if defined(MBEDTLS_AESNI_C) && \
+    (defined(MBEDTLS_HAVE_X86_64) || defined(MBEDTLS_HAVE_X86))
 
 /* Can we do AESNI with intrinsics?
  * (Only implemented with certain compilers, only for certain targets.)