Fine tuning tile sizes for ukernel RVV

This set of M, N K parameters are experimentally optimal through renode profiling.

Conv1x1 improvement as compared with generic tile sizes: 98.8% -> 98.0%
(lower bound 97.3% )

Change-Id: If40080620f61d4187ef5ef4c07e514101cc975a1

vmvx_ukernel/query_tile_sizes.c

diff --git a/vmvx_ukernel/query_tile_sizes.c b/vmvx_ukernel/query_tile_sizes.c
index 4f22c54..8a777aa 100644
--- a/vmvx_ukernel/query_tile_sizes.c
+++ b/vmvx_ukernel/query_tile_sizes.c
@@ -52,7 +52,7 @@
 static iree_uk_matmul_tile_sizes_t iree_uk_query_matmul_tile_sizes_rvv(
     const iree_uk_query_tile_sizes_2d_params_t* params) {
   (void)params;
-  return (iree_uk_matmul_tile_sizes_t){.M = 8, .K = 16, .N = 8};
+  return (iree_uk_matmul_tile_sizes_t){.M = 16, .K = 16, .N = 16};
 }
 
 static void iree_uk_query_tile_sizes_2d_matmul(