psa: Move from validate_key to import_key entry point

In the course of the development of the PSA unified
driver interface, the validate_key entry point for
opaque drivers has been removed and replaced by an
import_key entry point. This commit takes into account
this change of specification.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/src/drivers/key_management.c b/tests/src/drivers/key_management.c
index 00d2b45..ab3210b 100644
--- a/tests/src/drivers/key_management.c
+++ b/tests/src/drivers/key_management.c
@@ -137,11 +137,14 @@
     return( PSA_ERROR_NOT_SUPPORTED );
 }
 
-psa_status_t test_transparent_validate_key(
+psa_status_t test_transparent_import_key(
     const psa_key_attributes_t *attributes,
     const uint8_t *data,
     size_t data_length,
-    size_t *bits )
+    uint8_t *key_buffer,
+    size_t key_buffer_size,
+    size_t *key_buffer_length,
+    size_t *bits)
 {
     ++test_driver_key_management_hooks.hits;