sched_ext: Fix invalid irq restore in scx_ops_bypass()

In the Linux kernel, the following vulnerability has been resolved:

sched_ext: Fix invalid irq restore in scx_ops_bypass()

While adding outer irqsave/restore locking, 0e7ffff1b811 ("scx: Fix raciness

in scx_ops_bypass()") forgot to convert an inner rq_unlock_irqrestore() to

rq_unlock() which could re-enable IRQ prematurely leading to the following

warning:

raw_local_irq_restore() called with IRQs enabled

WARNING: CPU: 1 PID: 96 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x30/0x40

...

Sched_ext: create_dsq (enabling)

pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)

pc : warn_bogus_irq_restore+0x30/0x40

lr : warn_bogus_irq_restore+0x30/0x40

...

Call trace:

warn_bogus_irq_restore+0x30/0x40 (P)

warn_bogus_irq_restore+0x30/0x40 (L)

scx_ops_bypass+0x224/0x3b8

scx_ops_enable.isra.0+0x2c8/0xaa8

bpf_scx_reg+0x18/0x30

...

irq event stamp: 33739

hardirqs last enabled at (33739): [<ffff8000800b699c>] scx_ops_bypass+0x174/0x3b8

hardirqs last disabled at (33738): [<ffff800080d48ad4>] _raw_spin_lock_irqsave+0xb4/0xd8

Drop the stray _irqrestore().