Bugfix: Align calculation of number of ghost layers on GPU with CPU version

For the calculation of the number of ghostlayers only relative accesses should be considered like on the CPU version

pystencils/gpucuda/kernelcreation.py

@@ -27,6 +27,7 @@ def create_cuda_kernel(assignments,
     num_buffer_accesses = 0
     for eq in assignments:
         field_accesses.update(eq.atoms(Field.Access))
+        field_accesses = {e for e in field_accesses if not e.is_absolute_access}
         num_buffer_accesses += sum(1 for access in eq.atoms(Field.Access) if FieldType.is_buffer(access.field))
 
     common_shape = get_common_shape(fields_without_buffers)