samples: tfm_integration: Rename sample psa_level_1 to psa_crypto

The example in folder `samples/tfm_integration/psa_level_1` contains
code that demonstrate usage of PSA crypto APIs in Zephyr rather than the
PSA levels. Therefore renaming the sample as `psa_crypto`.

Signed-off-by: Devaraj Ranganna <devaraj.ranganna@linaro.org>