Fix(hsolver): sync d_eigenvalue before GPU refresh in Diago_DavSubspace (#7743)

The GPU path of Diago_DavSubspace::refresh() reads this->d_eigenvalue
which was last synchronized in cal_grad() — before diag_zhegvx()
computed the latest eigenvalues. This caused the restarted subspace
Hamiltonian to receive stale diagonal entries on GPU, leading to:
- Davidson eigenvalue oscillation and divergence
- Non-positive-definite overlap matrix
- zhegvx failure and zeroed wavefunctions

The CPU path already used the up-to-date eigenvalue_in_hsolver argument.
Fix the GPU path to re-sync d_eigenvalue from eigenvalue_in_hsolver.

Bug introduced by 8f7d319 (PR #6493).

Co-authored-by: dyzheng <zhengdy@bjaisi.com>

Author: dyzheng

source/source_hsolver/diago_dav_subspace.cpp

@@ -795,6 +795,9 @@ void Diago_DavSubspace<T, Device>::refresh(const int& dim,
 
     if (this->device == base_device::GpuDevice)
     {
+#if defined(__CUDA) || defined(__ROCM)
+        syncmem_var_h2d_op()(this->d_eigenvalue, eigenvalue_in_hsolver, nbase);
+#endif
         refresh_hcc_scc_vcc_op<T, Device>()(nbase, hcc, scc, vcc, this->nbase_x, this->d_eigenvalue, this->one_);
     }
     else