return_to_param: long to short should never return a longer version

return_to_param: long to short should never return a longer version

This is supposed to be looking for assignments like:

	struct foo *p = some->very->long_variable;

Because we refer to p->xxx instead of some->very->long_variable->xxx in
the code.  But sometimes we do things like:

	p = alloc();
	some->very->long_variable = p;

We'll still refer to p->xxx in the function, so we don't want to return the
long version of that variable.

I did some related cleanup as well.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>