uprobe_consumer->filter() is pointless in its current form, kill it.

We will add it back, but with the different signature/semantics. Perhaps
we will even re-introduce the callsite in handler_chain(), but not to
just skip uc->handler().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>