modules: tf-m: nordic: remove problematic include path

It made the build of
`samples/tfm_integration/tfm_psa_test/sample.tfm.psa_test_crypto`
break since the update of Mbed TLS to 3.6.0 (#71118), apparently because
`${ZEPHYR_BASE}` wasn't set, and the include doesn't seem to be needed.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>