Driver table entries are now mutable

Since driver table entries contain the driver context, which is
mutable, they can't be const anymore.
diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index eb24b6b..40e9683 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -168,7 +168,7 @@
 psa_status_t psa_validate_persistent_key_parameters(
     psa_key_lifetime_t lifetime,
     psa_key_file_id_t id,
-    const psa_se_drv_table_entry_t **p_drv,
+    psa_se_drv_table_entry_t **p_drv,
     int creating )
 {
     if( p_drv != NULL )