tests/qtest/cmsdk-apb-watchdog-test: Test INTEN as counter enable

tests/qtest/cmsdk-apb-watchdog-test: Test INTEN as counter enable

The following tests focus on making sure the counter is not running
out of reset and the proper use of INTEN as the counter enable. As
described in:

https://developer.arm.com/documentation/ddi0479/d/apb-components/apb-watchdog/programmers-model

The new tests have to target an MPS2 machine because the original
machine used by the test (stellaris) has a variation of the
cmsdk_apb_watchdog that locks INTEN when it is programmed to 1. The
stellaris machine also does not reproduce the problem of the counter
running out of cold reset due to the way the clocks are initialized.

Signed-off-by: Roque Arcudia Hernandez <roqueh@google.com>
Reviewed-by: Stephen Longfield <slongfield@google.com>
Message-id: 20241115160328.1650269-6-roqueh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>