x86/irq: fix reporting of spurious i8259 interrupts

x86/irq: fix reporting of spurious i8259 interrupts

The return value of bogus_8259A_irq() is wrong: the function will
return `true` when the IRQ is real and `false` when it's a spurious
IRQ.  This causes the "No irq handler for vector ..." message in
do_IRQ() to be printed for spurious i8259 interrupts which is not
intended (and not helpful).

Fix by inverting the return value of bogus_8259A_irq().

Fixes: 132906348a14 ('x86/i8259: Handle bogus spurious interrupts more quietly')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>