x86/IO-APIC: replace redundant irq_trigger() call

Just having called the function and stored the result, there's no point in
calling it again right away with the same argument; the stored result can
be used instead. And the stored result also doesn't need overwriting again
with the same value.

No functional change intended.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/arch/x86/io_apic.c

@@ -1089,10 +1089,8 @@ static void __init setup_IO_APIC_irqs(void)
             entry.trigger = irq_trigger(idx);
             entry.polarity = irq_polarity(idx);
 
-            if (irq_trigger(idx)) {
-                entry.trigger = 1;
+            if (entry.trigger)
                 entry.mask = 1;
-            }
 
             irq = pin_2_irq(idx, apic, pin);