genirq: Fix grammar s/an /a /

Fix a grammar mistake in <linux/interrupt.h>.

[ mingo: While at it also fix another similar error in another comment as well. ]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181008111726.26286-1-geert%2Brenesas@glider.beSigned-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/interrupt.h

@@ -45,7 +45,7 @@
  * IRQF_PERCPU - Interrupt is per cpu
  * IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
  * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
- *                registered first in an shared interrupt is considered for
+ *                registered first in a shared interrupt is considered for
  *                performance reasons)
  * IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
  *                Used by threaded interrupts which need to keep the

kernel/irq/irqdomain.c

@@ -867,7 +867,7 @@ void irq_dispose_mapping(unsigned int virq)
 EXPORT_SYMBOL_GPL(irq_dispose_mapping);
 
 /**
- * irq_find_mapping() - Find a linux irq from an hw irq number.
+ * irq_find_mapping() - Find a linux irq from a hw irq number.
  * @domain: domain owning this hardware interrupt
  * @hwirq: hardware irq number in that domain space
  */