ggml : do not break cuBLAS build (Q4_3 is not yet implemented)

ggml.c

@@ -8040,9 +8040,6 @@ static void ggml_compute_forward_mul_mat_q_f32(
         else if (type == GGML_TYPE_Q4_2) {
             dequantize_row_q_cuda = dequantize_row_q4_2_cuda;
         }
-        else if (type == GGML_TYPE_Q4_3) {
-            dequantize_row_q_cuda = dequantize_row_q4_3_cuda;
-        }
         else {
             GGML_ASSERT(false);
         }