Use remove_key_data_from_memory instead of wipe_key_slot

Since the loading attempt of a builtin key might be followed by trying
to load a persistent key, we can only wipe the allocated key data, not
the associated metadata.

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 068990a..f58df4a 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1063,8 +1063,7 @@
     psa_get_and_lock_key_slot_with_policy( key, p_slot, usage, alg )
 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
 
-/** Wipe key data from a slot. Preserve metadata such as the policy. */
-static psa_status_t psa_remove_key_data_from_memory( psa_key_slot_t *slot )
+psa_status_t psa_remove_key_data_from_memory( psa_key_slot_t *slot )
 {
     /* Data pointer will always be either a valid pointer or NULL in an
      * initialized slot, so we can just free it. */