cmake: limit Zephyr SDK to 0.16.x series for Zephyr 3.7 LTS

Zephyr SDK compatibility level 0.16 is now an LTS intended for
Zephyr v3.7 LTS.

Thus, limit the upper Zephyr SDK lookup to <0.17, so that developers
working with Zephyr v3.7 LTS and latest Zephyr main can install both
Zephyr SDK 0.16.x along side Zephyr SDK >=0.17 and have the Zephyr SDK
0.16.x series being used for v3.7 LTS development.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>