COMPMID-667: Add validation static method to NEON GEMMlowp

Change-Id: I8a470cc1351593ad8eeaf4ec92e04865e83d4f3c
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/96147
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
diff --git a/arm_compute/core/SubTensorInfo.h b/arm_compute/core/SubTensorInfo.h
index b8a3685..7c464c0 100644
--- a/arm_compute/core/SubTensorInfo.h
+++ b/arm_compute/core/SubTensorInfo.h
@@ -185,10 +185,11 @@
         ARM_COMPUTE_ERROR_ON(_parent == nullptr);
         return _parent->is_resizable();
     }
-    void set_is_resizable(bool is_resizable) override
+    ITensorInfo &set_is_resizable(bool is_resizable) override
     {
         ARM_COMPUTE_ERROR_ON(_parent == nullptr);
         _parent->set_is_resizable(is_resizable);
+        return *this;
     }
     ValidRegion valid_region() const override
     {