iosapic: fix a minor typo in comments

describeinterrupts -> describe interrupts
Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/iosapic.c

@@ -76,7 +76,7 @@
  *	PCI pin -> global system interrupt (GSI) -> IA-64 vector <-> IRQ
  *
  * Note: The term "IRQ" is loosely used everywhere in Linux kernel to
- * describeinterrupts.  Now we use "IRQ" only for Linux IRQ's.  ISA IRQ
+ * describe interrupts.  Now we use "IRQ" only for Linux IRQ's.  ISA IRQ
  * (isa_irq) is the only exception in this source code.
  */