FVP: Re-enable "Stats test cases after system suspend" test

The issue with the test has been fixed with the TF-A patch:
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3778


so re-enable it.

Signed-off-by: Zelalem <zelalem.aweke@arm.com>
Change-Id: Ie394b596c7da504c74c684af3ef5f6065a05eef9