genirq: Remove irq_[get|put]_desc*()

All users are converted to the guards. Remove the helpers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250429065422.729586582@linutronix.de