Only define validation test tolerance for quantized types in case of aarch64 for Neon™ Matmul

Partially Resovles: COMPMID-6026
Signed-off-by: Ramy Elgammal <ramy.elgammal@arm.com>
Change-Id: I273b213abba275f1609eae33058e3acbee2a7146
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/9489
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/tests/validation/NEON/MatMul.cpp b/tests/validation/NEON/MatMul.cpp
index 0f97dcf..0a20d18 100644
--- a/tests/validation/NEON/MatMul.cpp
+++ b/tests/validation/NEON/MatMul.cpp
@@ -45,8 +45,10 @@
 
 constexpr AbsoluteTolerance<float>   tolerance_fp32(0.001f); /**< Tolerance value for comparing reference's output against implementation's output for FP32 data types */
 const AbsoluteTolerance<half>        tolerance_fp16(half(0.1f));
+#ifdef __aarch64__
 constexpr AbsoluteTolerance<uint8_t> tolerance_qasymm8(0);
 constexpr AbsoluteTolerance<uint8_t> tolerance_qasymm8_signed(0);
+#endif // __aarch64__
 
 // clang-format off
 // *INDENT-OFF*