selftest/livepatch: Only run test-kprobe with CONFIG_KPROBES_ON_FTRACE

selftest/livepatch: Only run test-kprobe with CONFIG_KPROBES_ON_FTRACE

CONFIG_KPROBES_ON_FTRACE is required for test-kprobe. Skip test-kprobe
when CONFIG_KPROBES_ON_FTRACE is not set. Since some kernel may not have
/proc/config.gz, grep for kprobe_ftrace_ops from /proc/kallsyms to check
whether CONFIG_KPROBES_ON_FTRACE is enabled.

Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20250318181518.1055532-1-song@kernel.org
[pmladek@suse.com: Call grep with -q option.]
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>