cpu: x64: rnn: Fixed a bug that forced the usage of avx_512_core even when avx_512_core_vnni is available.

Author: davideberius

src/cpu/x64/rnn/rnn_brgemm_utils.cpp

@@ -85,7 +85,7 @@ x64::cpu_isa_t brgemm_calc_isa(
 
     if (rnn.is_cell_dt_int8()) {
         return utils::map(true, x64::isa_undef, mayiuse(avx512_core_vnni),
-                avx512_core, mayiuse(avx512_core), avx512_core);
+                avx512_core_vnni, mayiuse(avx512_core), avx512_core);
     } else if (rnn.is_cell_dt_bf16()) {
         return x64::avx512_core_bf16;
     } else if (rnn.is_cell_dt_f16()) {