fix avx2 int8 binary postops reg conflict

Author: luo-cheng2021

src/cpu/x64/jit_uni_x8s8s32x_conv_kernel.cpp

@@ -62,12 +62,9 @@ _jit_uni_x8s8s32x_fwd_kernel<isa, Vmm>::_jit_uni_x8s8s32x_fwd_kernel(
     if (jcp.with_eltwise || jcp.with_binary || jcp.with_sum || jcp.with_depthwise || jcp.with_quantization) {
         using namespace binary_injector;
         static constexpr bool preserve_gpr = true;
-        static constexpr bool preserve_vmm = false;
-        static constexpr size_t helper_vmm_idx = 15;
-        const size_t oc_block_tail = jcp.oc_block % isa_simd_width_;
-        const size_t tail_size = oc_block_tail
-                ? oc_block_tail
-                : jcp.oc_without_padding % isa_simd_width_;
+        static constexpr bool preserve_vmm = true;
+        static constexpr size_t helper_vmm_idx = 2;
+        const size_t tail_size = 0;
 
         const rhs_arg_static_params_t rhs_arg_static_params {helper_vmm_idx,
                 r13, r14, r15, preserve_gpr, preserve_vmm,