golang/xenlight: remove call to go fmt in gengotypes.py

golang/xenlight: remove call to go fmt in gengotypes.py

Since the golang bindings are now set to be re-generated whenever a
change is made to tools/libxl/libxl_types.idl, the call to go fmt in
gengotypes.py results in a dirty git tree for users without go
installed.

As an immediate fix, just remove the call to go fmt from gengotypes.py.
While here, make sure the DO NOT EDIT comment and package declaration
remain formatted correctly. All other generated code is left
un-formatted for now.

Signed-off-by: Nick Rosbrook <rosbrookn@ainfosec.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
Remove trailing whitespace.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>