[TF-M] Supported versions of the Armclang compiler in the TF-M build

Dear all,

We are considering to drop support for older versions of the Armclang compiler (i.e. 6.7 and 6.9) to focus support on newer releases (thus increasing the requirement on Armclang version to 6.10 or higher).

https://developer.trustedfirmware.org/T392

https://review.trustedfirmware.org/c/trusted-firmware-m/+/1223

If you have any specific requirement to use Armclang 6.7 or 6.9, please get in touch here or on the review.

Thanks, Antonio