Build: Fix recommended tf-m-tests version

There is a typo in the version.txt for the recommended version
of tf-m-tests. It must TF-Mv2.2.0 and not TF-Mv2.1.0-RC2

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I0bdc76de0b7a7539ebe3bcad84d9111bcd35150c
1 file changed