Compute Hard-Swish with a Lookup table for qasymm8_signed.

* Resolves COMPMID-5211

Change-Id: I7cc72662bb1cf52bf112685639d3dbba33d1333f
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7993
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/core/QuantizationInfo.h b/arm_compute/core/QuantizationInfo.h
index ed1025e..ddf1342 100644
--- a/arm_compute/core/QuantizationInfo.h
+++ b/arm_compute/core/QuantizationInfo.h
@@ -409,6 +409,16 @@
     return tmp;
 }
 
+inline qasymm8_signed_t qasymm8_signed_hard_swish(qasymm8_signed_t               in,
+                                                  const UniformQuantizationInfo &qi_in,
+                                                  const UniformQuantizationInfo &qi_out)
+{
+    float tmp_f         = dequantize_qasymm8_signed(in, qi_in);
+    tmp_f               = tmp_f * ((std::min(std::max((tmp_f + 3), 0.0f), 6.0f)) * 0.166666667f);
+    const qasymm8_t tmp = quantize_qasymm8_signed(tmp_f, qi_out);
+    return tmp;
+}
+
 inline qasymm8_t qasymm8_leaky_relu(qasymm8_t                      in,
                                     const UniformQuantizationInfo &qi_in,
                                     const UniformQuantizationInfo &qi_out,