Fix global_grid call in poisson.py

Author: kburns

examples/lbvp_2d_poisson/poisson.py

@@ -64,8 +64,8 @@
 solver.solve()
 
 # Gather global data
-x = xbasis.global_grid()
-y = ybasis.global_grid()
+x = xbasis.global_grid(dist, scale=1)
+y = ybasis.global_grid(dist, scale=1)
 ug = u.allgather_data('g')
 
 # Plot