db: fix how the return values are casted

db: fix how the return values are casted

Say you have:

int foo(void)
{
	unsigned char val;
	...
	return val;
}

We don't know the value of "val".  So the right thing to do is take the
whole range of val (0-255) and cast it to int and that's the return ranges.

Before we just took the whole range of int.

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