Disable MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT for armclang

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 353ec69..7bac408 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -3479,6 +3479,10 @@
     scripts/config.py baremetal
     # armc[56] don't support SHA-512 intrinsics
     scripts/config.py unset MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
+
+    # stop armclang warning about feature detection for A64_CRYPTO
+    scripts/config.py unset MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT
+
     scripts/config.py set MBEDTLS_HAVE_ASM
 
     make CC="$ARMC5_CC" AR="$ARMC5_AR" WARNING_CFLAGS='--strict --c99' lib