futex: Rename: match_futex()

In order to prepare introducing these symbols into the global
namespace; rename:

  s/match_futex/futex_match/g

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@collabora.com>
Link: https://lore.kernel.org/r/20210923171111.300673-12-andrealmeid@collabora.com