fix(dftu): restore cal_eff_pot_mat_R_{double,complex_double} function names

Commit 5ac6ca7 claimed 'R-space versions cal_eff_pot_mat_R_* kept
as-is for follow-up' in its message, but actually renamed the
function definitions in dftu_hamilt.cpp to cal_pot_uterm_mat_R_*.
The member declarations in dftu_lcao.h were not renamed, causing
header/implementation mismatch:

  dftu_hamilt.cpp:127: error: no declaration matches
    'void Plus_U::cal_pot_uterm_mat_R_double(int, double*, double*, int)'
  dftu_hamilt.cpp:157: error: no declaration matches
    'void Plus_U::cal_pot_uterm_mat_R_complex_double(...)'

Restore the original names cal_eff_pot_mat_R_double and
cal_eff_pot_mat_mat_R_complex_double in dftu_hamilt.cpp so they match
the declarations in dftu_lcao.h:80,82 and the call sites in
spar_u.cpp:76,195.

The R-space functions will be renamed in a follow-up commit that
also updates spar_u.cpp and the header in lock-step.

Verification:
- rg 'cal_pot_uterm_mat_R' returns no matches (no stale callers).
- rg 'cal_eff_pot_mat_R' shows consistent use across
  dftu_lcao.h (declarations), dftu_hamilt.cpp (definitions),
  spar_u.cpp (call sites).

Author: abacus_fixer

source/source_lcao/module_dftu/dftu_hamilt.cpp

@@ -124,7 +124,7 @@ void pot_uterm_real(Plus_U& dftu,
 
 } // namespace DFTU_LCAO
 
-void Plus_U::cal_pot_uterm_mat_R_double(const int ispin, double* SR, double* HR, const int npol)
+void Plus_U::cal_eff_pot_mat_R_double(const int ispin, double* SR, double* HR, const int npol)
 {
     const char transN = 'N', transT = 'T';
     const int one_int = 1;
@@ -154,7 +154,7 @@ void Plus_U::cal_pot_uterm_mat_R_double(const int ispin, double* SR, double* HR,
     return;
 }
 
-void Plus_U::cal_pot_uterm_mat_R_complex_double(const int ispin, std::complex<double>* SR, std::complex<double>* HR, const int npol)
+void Plus_U::cal_eff_pot_mat_R_complex_double(const int ispin, std::complex<double>* SR, std::complex<double>* HR, const int npol)
 {
     const char transN = 'N', transT = 'T';
     const int one_int = 1;