fix(gpu): enable gemm

Author: andrei-stoian-zama

backends/tfhe-cuda-backend/cuda/src/crypto/keyswitch.cuh

@@ -404,7 +404,7 @@ void execute_keyswitch_async(CudaStreams streams,
     Torus *current_lwe_input_indexes =
         get_variant_element(lwe_input_indexes, i);
 
-    if (false && (num_samples_on_gpu >= 144)) {
+    if (num_samples_on_gpu >= 144) {
       // Compute Keyswitch
       host_gemm_keyswitch_lwe_ciphertext_vector<Torus>(
           streams.stream(i), streams.gpu_index(i), current_lwe_array_out,