arm: timer: Take into account other wake-up events for the TVAL test

The TVAL test programs the timer to fire into the future, waits for an
interrupt using the WFI instruction, and when the instruction completes it
checks that the timer interrupt has fired. According to ARM DDI 0487G.a
there are other wake-up events that can cause the WFI to complete (listed
on page D1-2520), among them interrupts routed to a higher exception level,
where the hypervisor is running (if running under virtualization) or
firmware (if running on baremetal).

In practice, this is unlikely to have caused a false test failure, because
for a GICv3 (which the author assumes is a lot more common than a GICv4+)
the WFI is trapped by KVM and the VCPU thread is resumed only after the
timer asserts the interrupt, as the test expects.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Message-Id: <20211207154641.87740-5-alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>