pk: fixing backport issues

Note: RSA is not supported in mbedtls-2.28 for opaque wrapping
so it was removed from test_suite_pkwrite.data.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/pk.c b/library/pk.c
index 97984f3..12f4120 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -672,7 +672,7 @@
     status = psa_import_key(&attributes, d, d_len, key);
     mbedtls_platform_zeroize(d, sizeof(d));
     if (status != PSA_SUCCESS) {
-        return PSA_PK_TO_MBEDTLS_ERR(status);
+        return MBEDTLS_ERR_PK_HW_ACCEL_FAILED;
     }
 
     /* make PK context wrap the key slot */