fixup: api: ukernel: make get_B_pack_type static for better usability

Handle unsupported platforms gracefully.

examples/ukernels/cpu_brgemm.cpp

@@ -66,8 +66,17 @@ void brgemm_example() {
     // packing requirements once for multiple objects.
     // Based on this information, specific `ldb` value can be used, since
     // transform has a limited set of values supported.
-    const bool need_pack
-            = brgemm::get_B_pack_type(a_dt, b_dt) == pack_type::pack32;
+    bool need_pack = false;
+    try {
+        need_pack = brgemm::get_B_pack_type(a_dt, b_dt) == pack_type::pack32;
+    } catch (error &e) {
+        if (e.status == dnnl_unimplemented)
+            throw example_allows_unimplemented {
+                    "Kernel is not supported on this platform.\n"};
+
+        // on any other error just re-throw
+        throw;
+    }
 
     const memory::dim lda = K;
     // `ldb` for `need_pack = true` must be one of 16, 32, 48, or 64. This

src/cpu/x64/brgemm/capi/brgemm_api.cpp

@@ -168,7 +168,7 @@ status_t brgemm_t::get_B_pack_type(
     brgemm_utils::set_isa_impl(&brg);
     if (brg.isa_impl == cpu_isa_t::isa_undef) {
         VCHECK_BRGEMM_STATUS(
-                status::invalid_arguments, false, "get_B_pack_type failed");
+                status::unimplemented, false, "get_B_pack_type failed");
     }
     const bool has_vnni_layout = brgemm_desc_t::is_b_data_layout_vnni(
             dt_a, dt_b, /* brgattr.b_is_vnni = */ false, brg.isa_impl);