ewald-gpu: Sane default for Ewald tuning.

src/tcl/actor/Ewaldgpu_tcl.cpp

@@ -128,7 +128,7 @@ int tclcommand_inter_coulomb_parse_ewaldgpu_tune(Tcl_Interp * interp, int argc,
 	int num_ky=-1;
 	int num_kz=-1;
 	int K_max = 30;
-	int time_calc_steps = -1;
+	int time_calc_steps = 100;
 	double accuracy = 0.0001;
 	double precision = 0.000001;