param_key: use get_name_sym_from_key() instead of return_state_to_var_sym()
These functions are basically the same. I accidentally wrote two copies
of the same thing. The get_name_sym_from_key() is slightly more flexible
because it handles -2 params as well.
I haven't tested this patch. I'm trying to clean this up quickly. So I
will just test and apply fixes on top if something breaks.
Hopefully, we can move to just one var/sym to param/key code path and one
path to reverse the mapping.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>