simplify set device

Author: dzzz2001

source/module_hsolver/kernels/cuda/diag_cusolver.cu

@@ -6,8 +6,7 @@
 Diag_Cusolver_gvd::Diag_Cusolver_gvd(){
 // step 1: create cusolver/cublas handle
 #if defined(__MPI) && defined(__CUDA)
-    device_id = base_device::information::set_device_by_rank();
-    checkCudaErrors( cudaSetDevice(device_id) );
+    base_device::information::set_device_by_rank();
 #endif
     cusolverH = NULL;
     checkCudaErrors( cusolverDnCreate(&cusolverH) );

source/module_hsolver/kernels/cuda/diag_cusolver.cuh

@@ -22,7 +22,6 @@ class Diag_Cusolver_gvd{
 //-------------------
 
     cusolverDnHandle_t cusolverH = nullptr;
-    int device_id = 0;
 
     cusolverEigType_t itype = CUSOLVER_EIG_TYPE_1; //problem type: A*x = (lambda)*B*x
     cusolverEigMode_t jobz = CUSOLVER_EIG_MODE_NOVECTOR; // compute eigenvalues and eigenvectors.