KVM: selftests: Convert ARM's vGIC IRQ test to printf style GUEST_ASSERT

Use printf-based guest assert reporting in ARM's vGIC IRQ test.  Note,
this is not as innocuous as it looks!  The printf-based version of
GUEST_ASSERT_EQ() ensures the expressions are evaluated only once, whereas
the old version did not!

Link: https://lore.kernel.org/r/20230729003643.1053367-15-seanjc@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>