selftests: futex: Expand timeout test

Improve futex timeout testing by checking all the operations that
supports timeout and their available modes.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210427135328.11013-3-andrealmeid@collabora.com