arm: timer: Test CVAL before interrupt pending state

The timer pending test uses CVAL to trigger changes in the timer interrupt
state. Move the CVAL test before the pending test to make sure that writes
to the CVAL register have an effect on the timer internal state before
using the register for other tests.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Message-Id: <20211207154641.87740-4-alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>