futex: Move futex_queue() into futex_wait_setup()

futex: Move futex_queue() into futex_wait_setup()

futex_wait_setup() has a weird calling convention in order to return
hb to use as an argument to futex_queue().

Mostly such that requeue can have an extra test in between.

Reorder code a little to get rid of this and keep the hb usage inside
futex_wait_setup().

[bigeasy: fixes]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-4-bigeasy@linutronix.de