Fix compile error for Mbed TF-M V8M target

[ccli8]

[x] I confirm this contribution is my own and I agree to license it with Apache 2.0. [x] I confirm the moderators may change the PR before merging it in. [x] I understand the release model prohibits detailed Git history and my contribution will be recorded to the list at the bottom of CONTRIBUTING.md.

Summary of changes

This PR tries to fix compile error for Mbed TF-M V8M target, usually without FLASHIAP:

1. Use DEVICE_FLASH to exclude FLASHIAP code
2. Fix MBED_MAJOR_VERSION isn't available, which is needed to exclude mbedtls_psa_crypto_free().

[ccli8]

Have a look?

[marcuschangarm]

Thank you, I'll take a look.

[teetak01]

Thanks @ccli8 @marcuschangarm

I'll mark this for next public release as the changes have already been integrated internally.