build: Rename RECOMMEND_TFM_TESTS_VERSION to RECOMMENDED_TFM_TESTS_VERSION

Fix a typo.

Change-Id: Ic5ab3a492f5af7f45a6243eadf6c2e97f897bae7
Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>
1 file changed