doc: kernel: interrupts: correct description of irq lock behavior
doc: kernel: interrupts: correct description of irq lock behavior

Contrary to the documentation giving a semaphore while an IRQ lock is
held does not release the lock and give control to another thread.
The release-lock behavior is observed only if the lock-holding thread
sleeps.

However the opportunity to reschedule will have been lost so it may be
necessary to explicitly yield to allow the higher-priority thread to
be serviced.

Signed-off-by: Peter Bigot <a4112a160b558d5427af084318038e19a95979ee@nordicsemi.no>

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