selftests/ftrace: Fix to check required event file

The dynevent/test_duplicates.tc test case uses `syscalls/sys_enter_openat`
event for defining eprobe on it. Since this `syscalls` events depend on
CONFIG_FTRACE_SYSCALLS=y, if it is not set, the test will fail.

Add the event file to `required` line so that the test will return
`unsupported` result.

Fixes: 297e1dcd ("selftests/ftrace: Add selftest for testing duplicate eprobes and kprobes")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/ftrace/test.d/dynevent/test_duplicates.tc

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 # description: Generic dynamic event - check if duplicate events are caught
-# requires: dynamic_events "e[:[<group>/][<event>]] <attached-group>.<attached-event> [<args>]":README
+# requires: dynamic_events "e[:[<group>/][<event>]] <attached-group>.<attached-event> [<args>]":README events/syscalls/sys_enter_openat
 
 echo 0 > events/enable