Don't explicitly dereference function pointers

Be stylistically consistent.
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 84070c1..4bd2d13 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1231,9 +1231,9 @@
                    drv->key_management->p_export );
         if( method == NULL )
             return( PSA_ERROR_NOT_SUPPORTED );
-        return( ( *method )( drv_context,
-                             slot->data.se.slot_number,
-                             data, data_size, data_length ) );
+        return( method( drv_context,
+                        slot->data.se.slot_number,
+                        data, data_size, data_length ) );
     }
 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */