kernel: Rename UPROBE_EVENT to UPROBE_EVENTS

kernel: Rename UPROBE_EVENT to UPROBE_EVENTS

Upstream has renamed UPROBE_EVENT to UPROBE_EVENTS in the following
commit:

 commit 6b0b7551428e4caae1e2c023a529465a9a9ae2d4
 Author: Anton Blanchard <anton@samba.org>
 Date:   Thu Feb 16 17:00:50 2017 +1100

     perf/core: Rename CONFIG_[UK]PROBE_EVENT to CONFIG_[UK]PROBE_EVENTS

     We have uses of CONFIG_UPROBE_EVENT and CONFIG_KPROBE_EVENT as
     well as CONFIG_UPROBE_EVENTS and CONFIG_KPROBE_EVENTS.

     Consistently use the plurals.

So I'm changing it to this plural option in order to make kconfig happy
and stop asking about it if kernel is compiled with verbose logging:

 Enable uprobes-based dynamic events (UPROBE_EVENTS) [Y/n/?] (NEW)

Signed-off-by: Petr Štetiar <ynezz@true.cz>