sycl : port multi-column MMVQ from CUDA backend (llama/21845)

mmvq:

Port the ncols_dst optimization from ggml-cuda/mmvq.cu to SYCL.
Read weights once per dispatch instead of once per column.
Covers all standard quant types + reorder paths for Q4_0, Q8_0,
Q3_K, Q4_K, Q5_K, Q6_K. IQ types (except IQ4_XS) excluded due to
incompatible vec_dot signatures.

ggml-sycl:

The weight reorder was only bootstrapped on single-token mat-vec
(ne[1] == 1). Speculative / MTP verify issues only multi-column mat-vec,
so it never triggered the reorder and ran on the slower non-reorder
kernel. Bootstrap it on small multi-column batches (ne[1] <= 8) too.

ggml/src/ggml-sycl/ggml-sycl.cpp

@@ -3971,7 +3971,9 @@ static bool should_reorder_tensor(ggml_backend_sycl_context& ctx, const ggml_ten
     return !g_ggml_sycl_disable_optimize && //allow optimize, controlled by $GGML_SYCL_DISABLE_OPT
             ctx.opt_feature.reorder &&      //allow this device due to good perf, skip the devices with bad perf.
             dst->op == GGML_OP_MUL_MAT &&   //limit to some supported cases of Q4_0, to do for more cases.
-            dst->src[1]->ne[1]==1 && dst->src[1]->ne[2]==1 && dst->src[1]->ne[3]==1;
+            // ne[1] <= 8 so multi-column decode (spec / MTP verify) also bootstraps the reorder;
+            // all reorderable types have a _switch_ncols kernel.
+            dst->src[1]->ne[1] <= 8 && dst->src[1]->ne[2]==1 && dst->src[1]->ne[3]==1;
 }
 
 static void opt_for_reorder(ggml_backend_sycl_context * ctx, const ggml_tensor * src0, const ggml_tensor * /* src1 */,