Update heuristic for MatMul Native U8

Resolves COMPMID-6479

Signed-off-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
Change-Id: I13aa0ef944a75ba8b5e4df183d52df57b9aba90f
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10659
Reviewed-by: SiCong Li <sicong.li@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/runtime/heuristics/matmul_native/ClMatMulNativeDefaultConfigValhall.cpp b/src/runtime/heuristics/matmul_native/ClMatMulNativeDefaultConfigValhall.cpp
index 6b64141..4b92354 100644
--- a/src/runtime/heuristics/matmul_native/ClMatMulNativeDefaultConfigValhall.cpp
+++ b/src/runtime/heuristics/matmul_native/ClMatMulNativeDefaultConfigValhall.cpp
@@ -109,7 +109,7 @@
     unsigned int m, unsigned int n, unsigned int k, unsigned int b, bool rhs_lock_padding, const MatMulInfo &info)
 {
     ARM_COMPUTE_UNUSED(m, n, k, b, rhs_lock_padding);
-    return {info.adj_lhs(), info.adj_rhs(), /* m0 */ 1, /* n0 */ 16, /* k0 */ 4, /* export_to_cl_image */ false};
+    return {info.adj_lhs(), info.adj_rhs(), /* m0 */ 4, /* n0 */ 16, /* k0 */ 4, /* export_to_cl_image */ false};
 }
 
 MatMulKernelInfo ClMatMulNativeDefaultConfigValhall::configure_G710_f32(