selftests/ftrace: Update synthetic event syntax errors

Some of the synthetic event errors and positions have changed in the
code - update those and add several more tests.

Also add a runtime check to ensure that the kernel supports dynamic
strings in synthetic events, which these tests require.

Link: https://lkml.kernel.org/r/51402656433455baead34f068c6e9466b64df9c0.1612208610.git.zanussi@kernel.org

Fixes: 81ff92a9

 (selftests/ftrace: Add test case for synthetic event syntax errors)
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>