selftests/bpf: Change uretprobe syscall number in uprobe_syscall test

Fixing the syscall number value.

Link: https://lore.kernel.org/all/20240712135228.1619332-3-jolsa@kernel.org/

Fixes: 9e7f74e6

 ("selftests/bpf: Add uretprobe syscall call from user space test")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>