param_limit: handle struct members

param_limit: handle struct members

PARAM_LIMIT is code like this:

int is_ok(struct foo *p)
{
	if (p->bar >= 0 && p->bar < 100)
		return 1;
	return 0;
}

PARAM_FILTER looks like this:

void some_func(struct foo *p)
{
	if (p->bar < 0 || p->bar >= 100)
		p->bar = 0;
}

In the original code, if it was a parameter "$" then we limited it, but
if it was a struct member "$->bar" then we filtered it.  This was wrong
and it caused some false positives.  Also a struct member can be both
limited and filtered so the ordering has to be handle the limits first and
then the filtering.

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