selftests/ftrace: Fix to test kprobe $comm arg only if available

selftests/ftrace: Fix to test kprobe $comm arg only if available

BugLink: https://bugs.launchpad.net/bugs/1854975
[ Upstream commit 2452c96e617a0ff6fb2692e55217a3fa57a7322c ]

Test $comm in kprobe-event argument syntax testcase
only if it is supported on the kernel because
$comm has been introduced 4.8 kernel.
So on older stable kernel, it should be skipped.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>