fix "make generated_files" for test_keys.h and test_certs.h

This also add the check in tests/scripts/check-generated-files.sh

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/scripts/check-generated-files.sh b/tests/scripts/check-generated-files.sh
index 2f20026..96f1221 100755
--- a/tests/scripts/check-generated-files.sh
+++ b/tests/scripts/check-generated-files.sh
@@ -131,6 +131,7 @@
 check tests/scripts/generate_bignum_tests.py $(tests/scripts/generate_bignum_tests.py --list)
 check tests/scripts/generate_ecp_tests.py $(tests/scripts/generate_ecp_tests.py --list)
 check tests/scripts/generate_psa_tests.py $(tests/scripts/generate_psa_tests.py --list)
+check tests/scripts/generate_test_keys.py tests/src/test_keys.h
 check scripts/generate_driver_wrappers.py $library_dir/psa_crypto_driver_wrappers.h $library_dir/psa_crypto_driver_wrappers_no_static.c
 
 # Additional checks for Mbed TLS only