genirq: Fix typo in IRQ_NOTCONNECTED comment

Fix a minor typo in the comment for IRQ_NOTCONNECTED:
"distingiush" is corrected to "distinguish".

Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250410105144.214849-1-yphbchou0911@gmail.com